Effect of Acidic Beverages on the Hardness, Elastic Modulus and Wear Resistance of Giomer and Nongiomer Bulk-fill Materials.

OBJECTIVES: The aim of this study was to evaluate and compare the effect of acidic beverages on the hardness, elastic modulus, and wear resistance of four different resin-based restorative materials. METHODS AND MATERIALS: A total of 128 specimens (10 mm diameter, 4 mm thickness) were prepared from a conventional resin composite (Filtek Z250 [Z250]), a giomer bulk-fill (Beautifil Bulk Restorative [BBR]) and two nongiomer bulk-fill materials (Tetric N-Ceram Bulk Fill [TNC] and SonicFill 2 [SF2]). Each material group was divided into four subgroups (n=8) according to the storage media: artificial saliva (control), orange juice, regular Coke, and sports drink. The experimental specimens were immersed in the solutions for 30 minutes, five times a day for 5 days and kept in artificial saliva for an hour between the immersion periods. Control specimens were stored in artificial saliva for 5 days. The nanoindentation test with a Berkovich diamond tip was used to determine the hardness and elastic modulus before and after the 5-day storage periods. Following the nanoindentation tests, the specimens were subjected to a chewing simulator for 120,000 cycles. The specimens were then scanned with a three-dimensional scanner. The wear resistance was analyzed by measuring the volume and height loss. Specimens were observed by environmental scanning electron microscopy. The statistical analyses were performed by analysis of variance, Tukey HDS test, and paired samples t-test (α=0.05). RESULTS: Z250 showed significantly higher elastic modulus in all groups (p<0.05). After erosive cycles, the greatest decrease in hardness and elastic modulus was observed for BBR. TNC showed higher wear resistance than the other resin-based materials (p<0.05). The BBR specimens immersed in acidic solutions showed higher wear rates than the artificial saliva group (p<0.05). CONCLUSIONS: Conventional resin composite showed higher hardness and elastic modulus than bulk-fill materials when exposed to acidic beverages but comparable or lower wear resistance. Degradation due to acidic beverages most affected the mechanical properties of giomer bulk-fill.

Three-year Clinical Performance of Two Giomer Restorative Materials in Restorations.

CLINICAL RELEVANCE: The clinical performance of both conventional and flowable giomer restorative materials was particularly good in Class I restorations after three years of service. SUMMARY: This study evaluated and compared the clinical performance of a flowable and a conventional giomer restorative material after three years. Forty-four pairs of restorations (total n=88) were placed in Class I cavities with either a flowable giomer (Beautifil Flow Plus F00; Shofu Inc, Kyoto, Japan) or a conventional giomer restorative material (Beautifil II; Shofu Inc) after the application of a dentin adhesive (FL-Bond II; Shofu Inc) and a flowable liner (Beautifil Flow Plus F03; Shofu Inc). After 3 years, 39 pairs of restorations were evaluated with the modified United States Public Health Service criteria, and digital color photographs of restorations were taken at each patient visit. The evaluation parameters were as follows: color match, marginal integrity, marginal discoloration, retention, secondary caries formation, anatomic form, surface texture, and postoperative sensitivity. Evaluations were recorded as a clinically ideal situation (Alpha), a clinically acceptable situation (Bravo), or a clinically unacceptable situation (Charlie). Data were analyzed with Fisher's exact and McNemar tests (α=0.05).None of the restorations showed retention loss, postoperative sensitivity, secondary caries, or color change. The performance of Beautifil II in terms of marginal integrity, marginal discoloration, and surface anatomic form was significantly lower at the 36-month follow-up than at baseline (p=0.007). There were no significant differences between the baseline and 36-month follow-up scores for the other criteria for Beautifil II (p>0.05). No differences were found between the baseline and the 36-month follow-up scores for any of the criteria for Beautifil Flow Plus F00 (p>0.05). No statistically significant difference in overall clinical performance was found between the 2 materials after 36 months (p>0.05).The three-year clinical performance of both restorative materials (Beautifil Flow Plus F00 and Beautifil II) was very good and not significantly different for any of the parameters evaluated.

Accelerated forgetting and verbal memory consolidation process in idiopathic nondement Parkinson's disease.

OBJECTIVE: Episodic memory impairment and underlying pathophysiology in Parkinson's Disease (PD) is poorly investigated. Formerly, it was thought to be a secondary effect of impairment in fronto-striatal circuit. However, recent studies hypothesized that there is a dual progression of PD and memory loss is possibly related to posterior cortex rather than frontal. To understand the impairment, underlying mechanisms should be investigated. Although consolidation is one of these mechanisms consolidation phase of episodic memory in PD was not investigated yet. Recently accelerated long term forgetting (ALF) phenomenon is emphasized in consolidation researches. METHOD: Here it is evaluated the presence of accelerated long-term forgetting in nondemented PD as a consequence of a deficit in consolidation process. 32 patients and 33 controls participated in the study. Turkish Verbal Memory Process Test (VMPT) was applied to both groups. Delayed recall (DR) scores collected after 30 min, one week and six weeks. Forgetting rates were calculated based on these scores. RESULTS: There was significant difference in DR scores of patients compared to controls in the 30th minute and sixth week. Forgetting rate between 30th minute-1st week did not differ but 1st-6th week was found statistically significant across groups. CONCLUSIONS: To the best of our knowledge, this is the first study investigating verbal memory consolidation in PD. Results suggested that impairment is possibly related to the late phase of consolidation of verbal memory in neocortex.

Genetic evaluation of remnant and translocated shiners, Notropis heterodon and Notropis heterolepis.

Population and conservation genetics of two freshwater fish species, Notropis heterodon and Notropis heterolepis, were evaluated in north-eastern Illinois, U.S.A., where both species have severely declined. Fishes were sampled from two remnant populations occurring in small glacial lakes (source samples) and from two man-made ponds that had been stocked with fishes from those same lakes (sanctuary samples). The goal was to obtain information that would help inform conservation programme planning to reintroduce sanctuary fishes to areas where both species are extirpated. Microsatellite data showed that the two species were genetically quite distinct and there was no evidence of hybridization in either source or sanctuary samples. Within each species, source and sanctuary samples had moderate levels of heterozygosity and were not significantly different from each other. Many alleles observed in the source samples, however, were not detected in the sanctuary samples, indicating that translocation had resulted in reduced allelic diversity of the sanctuary samples. Sibship analysis indicated that full and half sibs occurred within source-lake samples, thus reducing the effective population size of the reintroduced stock. Taken together, these results suggest that source-lake stocks rather than sanctuary stocks are more appropriate for future reintroductions of both species in their native range, unless sanctuary populations can be established with hundreds of fishes. Also, fishes should be harvested from multiple locations in source lakes to avoid over-representation of family groups.

Bond strength of self-etch adhesives after saliva contamination at different application steps.

This study evaluated and compared the effect of saliva contamination and possible decontamination methods on bond strengths of two self-etching adhesive systems (Clearfil SE Bond [CSE], Optibond Solo Plus SE [OSE]). Flat occlusal dentin surfaces were created on 180 extracted human molar teeth. The two bonding systems and corresponding composite resins (Clearfil AP-X, Kerr Point 4) were bonded to the dentin under six surface conditions (n=15/group): group 1 (control): primer/bonding/composite; group 2: saliva/drying/primer/bonding/composite; group 3: primer/saliva/rinsing/drying/primer/bonding/composite; group 4: primer/saliva/rinsing/drying/bonding/composite; group 5: primer/bonding (cured)/saliva/rinsing/drying/primer/bonding/composite; group 6: primer/bonding (cured)/saliva/removing contaminated layer with a bur/rinsing/drying/primer/bonding/composite. Shear bond strength was tested after specimens were stored in distilled water at 37°C for 24 hours. One-way analysis of variance and Tukey post hoc tests were used for statistical analyses. For CSE, groups 2, 3, and 4 and for OSE, groups 6, 2, and 4 showed significantly lower bond strengths than the control group (p<0.05). CSE groups 5 and 6 and OSE groups 3 and 5 revealed bond strengths similar to the control. When saliva contamination occurred after light polymerization of the bonding agent, repeating the bonding procedure recovered the bonding capacity of both self-etch adhesives. However, saliva contamination before or after primer application negatively affected their bond strength.

Clinical and radiological characteristics of tumefactive demyelinating lesions: follow-up study.

BACKGROUND: Demyelinating lesions over 20 mm in size, referred to as tumefactive demyelinating lesions, can be misdiagnosed as being either a tumor or an abscess. Although some radiological characteristics can help make a differential diagnosis easier, a cerebral biopsy may still be necessary. OBJECTIVE: Our objective was to assess the clinical characteristics of tumefactive lesions, with or without a diagnosis of multiple sclerosis (MS), and present follow-up data for 54 patients with tumefactive lesions. METHODS: Demographic, clinical, radiological and laboratory data were gathered and treatment responses were evaluated in a total of 54 patients from five medical centers. RESULT: Twenty-nine patients were diagnosed with tumefactive lesions at the onset, whereas 25 patients were diagnosed with tumefactive lesions after a diagnosis of MS. Median follow-up was 38.12 months. At final examination, 19 of the patients with a tumefactive lesion diagnosis at the onset eventually developed relapsing-remitting MS, while 10 remained with the condition as a clinically isolated syndrome. The tumefactive lesions studied were mostly focal, with closed-ring enhancement. We found that oligoclonal band positivity was less frequent in the patients with tumefactive onset. CONCLUSION: Although our demographic data were similar to formerly collected Turkish MS data, we found that the distribution of the patients' clinical course differed if there was an absence of primary progressive MS and that there was a lower frequency of secondary progressive MS cases in our group of patients. We believe that less frequent oligoclonal band positivity and the difference we witnessed in the clinical course of disease in our study groups suggest that there is a need for further studies to compare all the biological and immunological differences between MS and tumefactive lesion cases, in order to reveal whether there are different pathogenetic mechanisms involved.

The use of mouse models to investigate shear bond strength in amelogenesis imperfecta.

Patients with amelogenesis imperfecta (AI) have defective enamel; therefore, bonded restorations of patients with AI have variable success rates. To distinguish which cases of AI may have good clinical outcomes with bonded materials, we evaluated etching characteristics and bond strength of enamel in mouse models, comparing wild-type (WT) with those having mutations in amelogenin (Amelx) and matrix metalloproteinase-20 (Mmp20), which mimic 2 forms of human AI. Etched enamel surfaces were compared for roughness by scanning electron microscopy (SEM) images. Bonding was compared through shear bond strength (SBS) studies with 2 different systems (etch-and-rinse and self-etch). Etched enamel surfaces of incisors from Amelx knock-out (AmelxKO) mice appeared randomly organized and non-uniform compared with WT. Etching of Mmp20KO surfaces left little enamel, and the etching pattern was indistinguishable from unetched surfaces. SBS results were significantly different when AmelxKO and Mmp20KO enamel surfaces were compared. A significant increase in SBS was measured for all samples when the self-etch system was compared with the etch-and-rinse system. We have developed a novel system for testing shear bond strength of mouse incisors with AI variants, and analysis of these data may have important clinical implications for the treatment of patients with AI.

Effect of Er,Cr:YSGG laser on the microtensile bond strength of two different adhesives to the sound and caries-affected dentin.

OBJECTIVE: This study examined the effect of Er,Cr:YSGG laser irradiation on the microtensile bond strength (microTBS) of a three-step etch-and-rinse and a two-step self-etch adhesive to sound and caries-affected dentin. METHODS: Sixteen freshly extracted human molars with occlusal dentin caries were used. The caries lesion was removed by one of the following methods: conventional treatment with burs or Er,Cr:YSGG laser (Waterlase MD, Biolase). The adhesive systems (AdheSE, Ivoclar Vivadent and Scotchbond Multi Purpose, 3M ESPE) were applied to the entire tooth surface according to the manufacturers' instructions. Resin composites were applied to the adhesive-treated dentin surfaces and light-cured. Each tooth was sectioned into multiple beams with the "non-trimming" version of the microtensile test. The specimens were subjected to microtensile forces (BISCO Microtensile Tester, BISCO). The data was analyzed by three-way ANOVA and independent t-tests (p=0.05). RESULTS: Er,Cr:YSGG laser irradiation exhibited similar microTBS values compared to that of conventional bur treatment, regardless of the adhesive system and type of treated dentin. The self-etch system revealed lower microTBS values, both with conventional and laser treatment techniques, compared to the etch-and-rinse adhesive in sound and caries-affected dentin (p<0.05). CONCLUSION: Er,Cr:YSGG laser irradiation did not negatively affect the bonding performance of adhesive systems to sound and caries-affected dentin.

Effect of sodium phenytoin concentration on neural tube development in the early stages of chicken embryo development.

Animal and human research has shown that anticonvulsants are teratogens and pose a risk of causing fetal malformations. In various studies, the teratogenic effects of sodium phenytoin (PTH) in several systems have been investigated. Toe and finger, renal, and even facial malformations have been described in the literature. However, there is debate about whether the true risk of teratogenesis is lower or higher than previously reported for PTH. There is also little published information on the effect of this agent on neural tube closure in an embryological model. In this study, 0.1 mL of three different concentrations of PTH solution (mg/mL: 1, 3, 5) or vehicle was applied under the embryonic disc of specific pathogen-free Leghorn chicken embryos after 24 hours' incubation. Incubation was continued until 72 hours of maturation. At 72 hours, all embryos were evaluated macroscopically and microscopically. There were serious neural tube closure defects in the embryos administered large amounts (0.5 mg) of PTH, but doses of 0.1 mg (subtherapeutic concentration for humans) and 0.3mg (therapeutic concentration for humans) produced no statistically significant defects (p=0.05). The difference between the defects in the high concentration group and the other three groups was statistically significant. In our study PTH administered in a strict concentration regimen produced a lower level of neural tube closure-related defects than previously reported.

Surgical approaches for antrochoanal polyp: a comparative analysis.

OBJECTIVE: The aim of this study was to evaluate the clinical and histopathological characteristics of antrochoanal polyps (ACPs) and to perform a comparative analysis of surgical techniques in terms of recurrence. METHODS: The clinical, radiological and histopathological features of 42 patients with a diagnosis of ACP who underwent surgery in a period of 6 years (January 2000 - January 2006) were investigated retrospectively. Histopathological examinations were present for all patients and were re-examined for histological analysis. RESULTS: Endoscopic sinus surgery (ESS) was performed in all patients. Transcanine sinoscopy (TS) and the Caldwell-Luc approach (CL) were used in addition to ESS in 14 and 13 patients respectively. The attachment site was detected in 21 patients (50%) and the most frequent site was found to be the lateral wall in 15 patients (71.4%). There was no relationship between the choice of surgery, the attachment site or accessory ostium, or any sinusitis with ACP. Histological examination showed prominent eosinophilia in 29 patients (69%). The follow-up time was a minimum of 12 months with a mean of 28.9 months. Three recurrences were seen after ESS. However, there was no recurrence after ESS+TS and ESS+CL. CONCLUSION: Our study showed that the most important factors affecting the choice of surgical approaches are the preference of the surgeon, the age of the patient and the presence of recurrent disease. Combined approaches with either TS or CL should be considered, particularly when the attachment site of the antral part of ACP is undetected, in order to prevent incomplete excision and recurrences.

Quality of life after surgery for benign disease of the parotid gland.

OBJECTIVE: To evaluate quality of life after surgery for benign neoplastic disease of the parotid gland. PATIENTS AND METHODS: A quality of life questionnaire, which was created from the Hebrew version of the University of Washington Quality of Life prototype, was applied to 55 patients who underwent surgery for benign neoplastic parotid disease. All patients were examined in Baskent University Adana Teaching and Medical Research Center, where all except 10 subjects (who responded by phone) completed the quality of life questionnaire. RESULTS: The highest overall score was 96.3 indicating no salivary fistula. Only one patient complained of salivary secretion through the wound scar. The lowest overall score was 59.5 indicating loss of sensation. Although no post-surgical pain was reported by 32 (58 per cent) patients, 16 (29 per cent) patients reported a post-surgical change in their appearance. Scarring and surgical site depression were reported by 26 (47 per cent) and 17 patients (30 per cent), respectively. Facial nerve impairment was reported by seven patients (13 per cent) during the early post-operative period; these patients recovered from that impairment. The only significant statistical correlations were noted between general health and gender, and between post-surgical pain and gender. There was not any statistical correlation between all data and age, tumour type and education level. CONCLUSION: The general status of patients who have undergone surgery for a benign parotid neoplasm can be assessed with a quality of life questionnaire. Patients' post-surgical quality of life can be improved by the correct choice of surgical approach and reconstructive method.

Bactericidal efficacy of Er,Cr:YSGG laser irradiation against Enterococcus faecalis compared with NaOCl irrigation: an ex vivo pilot study.

AIM: To compare the efficacy of a standard NaOCl irrigation procedure with that of Er,Cr:YSGG laser irradiation in contaminated root canals having small and large apical foramina. METHODOLOGY: Forty root canals of extracted central incisor teeth with straight roots were chosen so that their apical foramina just permitted the tip of a size 20-K file to pass through. The canals were then enlarged with files to size 60 and randomly divided into four groups of 10 teeth each. The apical foramina of one group were widened further so that the tip of a size 45-K file could just pass through. After sterilization, all roots were inoculated with Enterococcus faecalis for 48 h at 37 degrees C. The first group was used as a control, the second group was irrigated with 3% NaOCl solution for 15 min, and the last two groups having different sizes of apical foramina were irradiated with the Er,Cr:YSGG laser at output power from 0.5 W, with 20% air and water levels. The disinfecting efficacy of the groups was tested by collecting dentine chips from the inner canal walls of the specimens and counting viable E. faecalis on Mueller-Hinton agar plates. RESULTS: The differences in the mean number of viable colonies between the control and laser groups were statistically significant (P < 0.05). The control specimens had the highest number of microorganisms (153 x 10(3) +/- 39 x 10(3)). Complete sterilization was achieved in the 3% NaOCl group. The mean colony forming units (CFU) values obtained after Er,Cr:YSGG laser irradiation were 6.6 x 10(3) CFU and 6.5 x 10(3) CFU in root canals having large and small apical foramina respectively. CONCLUSION: In teeth with straight roots the Er,Cr:YSGG laser reduced the viable microbial population in root canals with small and large apical foramina but did not eradicate all bacteria. Three percent NaOCl inhibited the growth of E. faecalis and effectively sterilized all root canals.

Thyroid cancer in hyperthyroidism: incidence rates and value of ultrasound-guided fine-needle aspiration biopsy in this patient group.

Three hundred and thirty-three hyperthyroidism cases were retrospectively investigated to provide information about the association between hyperthyroidism and thyroid cancer. There were 112 cases of toxic multinodular goiter (TMNG), 77 cases of toxic nodular goiter (TNG) and 144 cases of Graves' disease (GD). All nodules detected in GD patients, all nodules greater than 1 cm diameter in nodular goiter patients, nodules 5-10 mm size diameter if they had calcification were fine-needle biopsied (FNAB) under ultrasound guidance (US-guided), and a total of 612 such biopsies were performed. The biopsy samples were cytologically assessed as benign (no.=552; 90.2%), suspicious (no.=6; 1.1%), malignant (no.=13; 2.1%), or inadequate for diagnosis (no.=41; 6.7%). All patients with a biopsy diagnosis of malignant or suspicious nodules underwent surgery. Histological examination confirmed the diagnosis of thyroid cancer in all 13 (2.1%) patients with malignant FNAB findings. Papillary thyroid carcinoma (PTC) was identified in 2 patients with TMNG (%1.8), 5 with TNG (%6.5) and 5 with GD (%3.5). Metastatic follicular thyroid carcinoma (FTC) was identified in a patient with TNG. Thyroid malignancy (micro- or macrocarcinoma) was diagnosed pre-operatively in all 13 cases by US-guided FNAB. Thyroid cancer was diagnosed in 6 (5.5%) of the 109 nodules detected in the TNG group, 2 (0.44%) of the 452 nodules detected in the TMNG group, and 5 (9.8%) of the 51 nodules detected in the GD group. Two (2.6%) of the 77 functioning nodules in the TNG patients were malignant, but none of the 402 functioning nodules in the TMNG patients was malignant. In patients with hyperthyroidism, US-guided FNAB is useful for detecting thyroid cancer in nodules greater than 5 mm diameter before radioiodine therapy or surgery.

Antibacterial activities of MDPB and fluoride in dentin bonding agents.

The aim of this study was to compare in vitro antibacterial activity of MDPB containing bonding system ABF with activities of three Fluoride containing bonding systems (Fuji Bond LC (FBLC), Prime&Bond NT (PBNT), and FluoroBond (FLB). Two bacterial strains were tested: Streptococcus mutans and Lactobacillus acidophilus. The study was performed on Muller Hinton Agar by Agar Well Technique. The bacterial agar was evenly distributed over the surface of petri dishes. Standard wells were punched into the agar. The test materials were placed in the wells of Muller Hinton agar plates, inoculated with Streptococcus mutans NCTC10449 and Lactobacillus acidophilus. The diameters of inhibition zones produced around the materials were measured after 24 h of incubation at 37 +/- 1 degrees C. For statistical analysis, Duncan's multiple range test was used. The primers of bonding agents were highly effective against to Streptococcus mutans. The MDPB containing primer of ABF Bond produced the greatest inhibition zones against to Lactobacillus acidophilus. It was followed by FLB primer. Lactobacillus acidophilus was resistant to FBLC primer and bonding, ABF, PBNT and FLB bonding agents. The results of this study indicated that, incorporation of MDPB in primer of self-etch system increased its antibacterial activity especially against to Lactobacillus acidophilus. However, all bonding systems except for bonding agent of ABF showed some antibacterial activity against to Streptococcus mutans.

Evaluation of internal adaptation in ceramic and composite resin inlays by silicon replica technique.

This study was aimed at investigating the internal adaptation of a ceramic (Ceramco II) and two composite resin inlay materials (SureFil and 3M Filtek Z 250) using silicon replica technique as an indicator. Forty-five standard mesial-occlusal-distal (MOD) cavities were prepared into brass moulds by using computer numerically controlled system. Inlays were prepared according to manufacturers' instructions with indirect methods. Replicas of the prepared cavities and inlays were produced with a polyvinyl siloxane material (Elite H-D). The spaces between inlays and cavities were filled by different coloured light-body polyvinyl siloxane material. Two parallel slices (mesio-distally) were obtained from the replicas with a sharp blade. Different coloured polyvinyl siloxane material thickness between cavity and inlay was measured at seven points (mesial, occlusal and distal). The data were evaluated with anova and Tukey's honestly significantly different (HSD) statistical tests. In the SureFil and Ceramco II groups, the sizes of the contraction gaps at mesial and distal gingival floors were greater than that of the occlusal marginal walls. In comparison of gap formation at occlusal regions, while the 3M composite group showed highest gap values (204.33 +/- 75.45 microm), the Ceramco II group revealed the lowest (141.17 +/- 23.66 microm) (P < 0.05). At the gingival floors, gap formation of Ceramco II group was the highest (227.08 +/- 51.95 microm). Neither the 3M Filtek Z250 nor SureFil group showed any statistical difference between gap values of their self-occlusal and gingival floors (P > 0.05). In conclusion, our results showed that ceramic inlays did not confer any big advantage for internal adaptation over the composite inlays.

Tracheopathia osteoplastica associated with iron deficiency anemia.

Tracheopathia osteoplastica (TPO) is a benign disease of trachea characterised by numerous cartilaginous or bony structures protruding into tracheobronchial lumen. We report a case of a 85-year-old male patient in whom tracheopathia osteoplastica was diagnosed incidentally during bronchoscopy which was missed on chest computed tomography examination. The patient also had iron deficiency anemia, the cause of which was not identified. We review TPO and discuss the associated abnormalities reported in the literature.

Effect of home bleaching agents on the microhardness of human enamel and dentin.

In this study, the effects of home bleaching agents that contains carbamide peroxide (in different concentrations such as 10 and 15%) on the surface hardness of human enamel and dentine were evaluated. The buccal surfaces of 90 recently extracted human mandibular anterior teeth were used. The specimens in the dentine group were ground to expose of dentine surface. Then, samples in both enamel and dentine group were randomly divided into six main groups with 15 in each group. In the group 1 and 4, 15% carbamide peroxide was applied to the enamel and dentine surfaces and then the teeth were left in an incubator at 37 degrees C and 100% humidity for 4 h first, then left 28 h after repeating the same procedures seven times. The teeth were treated with 10% carbamide peroxide in groups 2 and 5 and distilled water in groups 3 and 6 (control groups), using the same procedures. Vicker's microhardness of enamel and dentine were assessed on each tooth before and after each treatment period (4 and 28 h). The hardness of control group specimens was also obtained after 4 h in distilled water and then after 28 h. For statistical analysis one-way ANOVA and post-hoc Tukey tests were used. For both 10 and 15%, there were no statistically significant differences between the untreated control specimens and the specimens treated with the bleaching materials for enamel and dentine at any given measurement time (P > 0.05). Nevertheless, in vivo use of bleaching agents on tooth hard tissues requires further analysis.

An in vitro comparison of adhesive systems to seal pulp chamber walls.

AIM: To compare in vitro the sealing properties of five different dentine adhesive materials (Prime&Bond NT (PBNT); Prompt L-Pop (PLP); Clearfil SE Bond (CSEB); Scotchbond Multi Purpose Plus (SMPP); EBS-Multi (EBSM)) inside the pulp chamber. METHODOLOGY: Seventy-five recently extracted human molar teeth were used. The roof of the pulp chambers and roots were removed under water cooling. Pulp tissue was removed, and the canal orifices were sealed. The pulp chambers were then treated with 5% sodium hypochlorite (NaOCl) for 1 min. The teeth were randomly divided into five groups of 15 teeth each. Adhesive systems were applied to the pulp chamber walls according to the manufacturers' instructions. The samples were connected to Plexiglass plates, and a fluid filtration method was used for quantitative evaluation of leakage. Measurements of fluid movement were made at 2-min intervals for 8 min. The quality of seal of each specimen was measured immediately, after 24 h, 1 week and 1 month. The data were statistically analysed by repeated-measurements multivariate anova, Friedman test, Wilcoxon signed rank test, Kruskal-Wallis of one-way anova and Mann-Whitney U-tests. The pulp chamber wall with and without NaOCl and resin-dentine interfaces of specimens were observed under a scanning electron microscope (SEM). RESULTS: The leakage values of the materials were significantly different at different measurement periods. In all groups, leakage values decreased with time (P < 0.05). PBNT and PLP had the least leakage during immediate measurements (P < 0.05). After 1 month, leakage of all adhesive systems was not significantly different (P < 0.05). SEM observation of pulp chamber walls demonstrated that the irregular dentine surface without smear layer was present in the nontreated group. However, NaOCl application removed the collagen fibrils leaving the dentine surface smooth. At resin-dentine interfaces of specimens, no hybridization zone was observed. CONCLUSIONS: None of the materials had created a perfect seal to the pulp chamber walls. PBNT and PLP had better sealing over the short term, but over the long term, there were no differences between the materials.

Influence of dentinal regions on bond strengths of different adhesive systems.

This in vitro study assessed comparatively the shear bond strengths of three composite resins, 3M Valux Plus (3MVP), Herculite (H), Clearfil AP-X (CAP-X), a polyacid modified composite resin Dyract (D), and a resin modified glass-ionomer materials Vitremer (V), to cervical and buccal dentine regions of extracted human molar teeth. Four different bonding systems, 3M ScotchBond Multipurpose (SB), Clearfil Liner Bond 2 (LB2), Opti Bond (OB), and Prime & Bond 2.1 (PB 2.1) were used with the manufacturer's respective composite and compomer materials. One hundred freshly extracted mandibular molar teeth were selected for this study. Flat buccal dentine surfaces were created on 50 teeth and cylindrical rods of the five materials were bonded to the dentine surfaces. For assessment of cervical bond strengths, the materials were bonded to mesial and distal enamel bordered occlusal dentinal surfaces of the remaining 50 teeth. The five groups of restorative procedures were applied as follows; Group 1: SB + 3MVP, Group 2: LB2 + CAP-X, Group 3: OB + H, Group 4: PB2.1 + D, Group 5: Vitremer primer (VP) VP + V. Each restorative procedure thus had 20 specimens (10 buccal + 10 cervical). After 24 h of water storage (37 degrees C), the specimens were tested on a Universal Testing machine in shear with a cross head speed of 0.5 mm min-1. The bond strength values were calculated in MPa and the results were evaluated statistically using Kruskal-Wallis one-way/anova and Mann-Whitney U-tests. It was found that the bond strengths of SB + 3MVP, LB2 + CAP-X and VP + V to buccal dentine surfaces were significantly stronger (P < 0.05) than those to the occluso-cervical dentine floors. When the bond strengths to the occluso-cervical dentine and buccal dentine surface were compared, there was no significant difference between the materials (P > 0.05). Vitremer was found the least successful adhesive material in terms of shear bond strength on both buccal and occluso-cervical dentine surfaces.

The effect of simulated intrapulpal pressure on bond strength to enamel and dentine.

The purpose of this study was to evaluate the effect of simulated intrapulpal pressure on the shear bond strength (SBS) of a self-etching bonding system (Clearfil Liner Bond II) to both enamel and dentine surfaces. Forty-two caries-free human molar teeth were randomly assigned to two equal groups (n=21). One group of 21 teeth was connected to a special pulpal pressure machine, which is developed to simulate in vivo conditions. The buccal and lingual surfaces of the teeth were prepared with a diamond wheel to create flat dentine and enamel surfaces. A self-etching bonding system was then applied under pulpal pressure and 2.5 mm diameter composite cylinders were bonded to the prepared surfaces. The samples were then stored in distilled water at room temperature for 24 h under pulpal pressure before SBS was tested. The second restored group was used as a control and the teeth were not connected to the pulpal pressure apparatus during material application and test procedures. They were stored for 24 h in distilled water at room temperature before the SBS test. Fracture analysis of the enamel and dentinal surfaces was performed using a stereomicroscope. Shear bond strength values to dentine was significantly reduced with pulpal pressure (P < 0.001). However, in the enamel, SBS was increased (P < 0.001). In the control group, the SBS values to dentine and enamel did not show any significant difference (P > 0.05). Based on these results, it can be concluded that further analysis of enamel histology and bonding mechanisms are needed.