[Effects of mouthwashes on color stubitity of hleached teeth]

Background and Aim: Bleached teeth are susceptible to discoloration. The aim of this study was to evaluate discoloration of bleached teeth following short-term use of several mouthwashes.

Materials and Methods: In this In-vitro experimental study, 48 extracted maxillary central incisorswere selected and divided into four groups of 12. All the teeth were subjected to external bleaching with 38% hydrogen peroxide [H2o2]. After bleaching, the teeth were immersed in in distilled water [control group or group 1], chlorhexidine [CIx; group 2], Irsha [group 3] or Persica [group 4] for three, seven and 14 days. The color change was assessed by a spectrophotometer at each time point and reported as INCREMENT El, INCREMENT E2 and INCREMENT E3. The results were analyzed by paired t-test, repeated measures ANOVA, one-way ANOVA and LSD test.

Results: Different mouthwashes [p:0.0a3] and immersion times [p:0.03g] caused significantly variable color change in bleached teeth. After 14 days of immersion, the color change of samples in Persica group had significant differences with that of other goups [p<0.000]. The results of repeated measures ANOVA was only significant for the persica group indicating significant color change over time. Thus, paired t-test was applied for pairwise comparison of the time points, which revealed significant differences between INCREMENT EI and INCREMENT E3 and also INCREMENT E2 and INCREMENT E3 [p<0.0S].

Conclasion: Persica mouthwash would cause significant discoloration in recently bleached teeth.

[Shear bond strength of composite to primary enamel treated with CPP-ACP using total-etch and self-etch bonding systems]

By application of case in phosphopeptide amorphous calcium phosphate [CPP-ACP] as are mineralizing agent, it may be feasible to only remove the carious dentin and better preserve the tooth structure. This study aimed to assess the shear bond strength of composite to primary enamel treated with CPP-ACP using total etch and self etch bonding systems. This in vitro experimental study was conducted on 96 sound primary teeth randomly divided into 12 groups [n=8]. Four groups were demineralized and the rest remained sound. All the specimens were subjected to pH cycling. Then, GC-Tooth Mousse was applied on their surfaces. Composite resin was bonded using Clear fil SE Bond self-etch or Single Bond total-etch bonding systems. The bond strength of the specimens was measured by Instron machine and the mode of fracture was assessed by a stereomicroscope. Data were analyzed by one-way and two-way ANOVA and chi-square test. In the total etch system, the bond strength of demineralized group was significantly higher than that of sound group [P=0.009].This difference in self etch system was not significant [P=0.928]. The CPP-ACP remineralizing agent decreased the bond strength in total etch and increased the bond strength in self etch group [P=0.032 and P=0.018, respectively]. No difference was observed in the mode of fracture of the two bonding systems.GC Tooth Mousse decreased the bond strength to composite in total etch and increased it in self etch group. Higher bond strength to composite can be achieved in teeth with white spot lesions when total etch system is used

[Comparative evaluation of the effect of CPP-ACP and resin infiltration on brown spot color parameters after using 20% carbamide peroxide]

Tooth colored restorations are the commonly used current approach for aesthetic problems associated with brown spots. Considering the importance of conservative dentistry, the aim of this in vitro study was to evaluate the efficacy of color correction using casein phophopeptide amorphous calcium phosphate [CPP-ACP] and resin infiltration after using 20% carbamide peroxide for brown spots in esthetic areas. In this experimental study, 70 humans teeth samples with brown spots were collected. In the first step, 20% carbamide peroxide was applied and then samples were divided into two groups to be treated with CPP-ACP or resin infiltration. Color parameters of the samples were evaluated at baseline, after bleaching, after using infiltration resin and CPP-ACP. Any color shift was measured using spectrophotometer. The results were analyzed by SPSS version 20. For statistical analysis, paired t test, indeipendent t-test and repeated measures ANOVA were used. P value <0.05 was considered significant. After using 20% carbamide peroxide, L[asterisk] and b[asterisk] increased and a [asterisk] decreased significantly [p<0.001]. By using CPP-ACP, decreases in a [asterisk] and b[asterisk] were not significant [p>0.05] but L[asterisk] increased significantly [p<0.001]. Application of infiltration resin caused a significant decrease in a [asterisk] [p<0.001]; however, the decrease in L[asterisk] and the increase in b[asterisk] were not statistically significant [p>0.05]. Comparison of the two groups showed that the degree of color shift [delta E] in brown spots and adjacent sound enamel did not change significantly in the two subgroups [p>0.05]. The results show that for esthetically unfavorable brown spots, using 20% carbamide peroxide with CPP-ACP or resin infiltration can improve the appearance. In general, application of resin infiltration with carbamide peroxide is preferably recommended for improving translucency

[Effect of translucency and opacity of fiber reinforced posts on fracture resistance of compromised teeth]

Severely damaged teeth with no support at the coronal portion of root canal are very difficult to restore. The aim of this invitro study was to evaluate intraradicular reinforcement by dual cure composite resin and two different types of fiber reinforced composite [FRC] posts [translucent and opaque] in structurally compromised roots. Root canal therapy was performed for 48 maxillary central incisors. The teeth were divided into four groups, and specimens from three groups were prepared to simulate the teeth with flared canals. In the 1[st] group, no weakening was done. In the 2[nd] group, the compromised area of the root canal was filled with gutta percha. In the 3[rd] and 4[th] groups, universal DT light and DT white posts were used respectively in the root canal to 8 mm below the margin of the palatal wall. The posts were cemented with dual-cure composite. In all groups, the access cavity was restored with light-cure compo-site resin. After being mounted, all specimens were pressed at an angle of 45? relative to the long axis of the teeth. The amount of force at fracture was recorded. Results of fracture load were evaluated by one-way ANOVA and LSD post hoc test and the results of mode of fracture were evaluated by chisquare test. The mean fracture load for the four groups was 170.12, 71.40, 125.8 and 148.59 kgf, respectively. There was a significant difference between the mean fracture load of 1[st] and 2[nd] groups and that of other groups [P=0.001]. The mean fracture load of the 4[th] group was significantly [P=0.002] higher than that of the 3[rd] group. The frequency of restorable fractures was significantly different between these two groups [P<0.001]. Using dual cure composite resin and FRC posts in roots with thin walls will reinforce the compromised teeth but the type of post will affect the outcome

[Changes in bleached enamel microhardness after application of fluoride and CPP-ACP]

Tooth bleaching decreases enamel microhardness. The aim of this study was to evaluate the changes in microhardness of bleached enamel after applying fluoride and CPP-ACP [casein phosphopeptide amorphous calcium phosphate]. In this experimental study, sixty extracted human molars were divided into six groups [ten each]. The flatted occlusal surface was covered with nail varnish. In the second, third and fourth groups, tooth bleaching was performed. The first and second groups were positive and negative control groups. In the third and fifth groups, the specimens were covered with sodium fluoride varnish and the fourth and sixth groups underwent CPP-ACP therapy. Subsurface enamel microhardness was determined on the occlusal surface with 300 micron distance from the buccal or lingual surface. One way ANOVA and Tukey post hoc were used for statistical analysis. Microhardness of bleached enamel was significantly lower than the other groups. The teeth treated by fluoride agent or CPP-ACP after bleaching had a significant increase in their microhardness in contrast with the bleached enamel. CPP-ACP and fluoride treatment had no significant effect on sound enamel microhardness. Although using CPP-ACP and fluoride increases the enamel microhardness, there was no significant differences between them. Fluoride and CPP-ACP components increase bleached enamel microhardness

[Effect of ultrasonic scaler on the microleakage of ClV tooth colored restorations]

Class V cavities are mostly filled with tooth colored restorations. Microleakage is an important problem with tooth colored restorations. Some studies show that ultrasonic scalers could cause microleakage. The aim of this study was to examine the effects of ultrasonic scaling on three different tooth colored restorations; namely, composite resin, glass-ionomer and comboglass. In this in-vitro study, sixty extracted premolars were randomly divided into three groups of 20 teeth. In all the teeth the same size class V cavity was prepared. First, second and third group teeth were filled with composite, gloss inomer and compoglass, respectively. After thermocycling, half of the teeth in each group were scaled with ultrasonic [test group]; whereas, the other half were used as control. Then, all the specimens were kept in 2% fuchsin for dye penetration testing for approximately 24 hours. After sectioning, the specimens' microleakage was quantified with steriomicroscope. The data were analyzed statistically by Kruskal-Wallis analysis and Mann-Whitney U-tests with Bonferroni's correction. In the first [composite] and third [compoglass] groups ultrasonic scaling had no effect on microleakage [P>0.05]; whereas, in the second group [glass-ionomer] ultrasonic scaling caused more microleakage than the control group. The difference was statistically significant [P<0.001]. The ultrasonic scaler should be used with caution around class V cavities filled with tooth colored restorations because of the possible microleakage effect

[Effect of used diamond burs on dentin bond strength]

Many researchers have reported that, constant use of diamond burs can reduce their cutting efficacy during cavity preparation. The aim of this study was to evaluate the effect of changes in diamond bur sharpness on dentin bond strength when using self-etch bonding system. A total of seventy-two caries-free human 3[rd] molars were included in this in-vitro investigation. The teeth were sectioned in occlusal surface in order to expose dentin, and then were randomly divided into four groups. For dentin preparation, a fine diamond bur was used in group 1, a new coarse diamond bur was used in group 2, a used coarse diamond bur was used in group 3 after applying on porcelain for two minutes, and a used coarse diamond bur was used in group 4 after it was applied on porcelain for ten minutes. Unique composite capsules were bonded to all dentin surfaces using Clearfil SE Bond and then cured. After storage for 24 hours in 37°C distilled water, the bonded teeth were subjected to shear testing by using Instron testing machine. The bond strengths were calculated and recorded as failure. Bond strength data were analyzed by One-Way ANOVA and Tukey tests. The mean [Standard Deviation] of shear bond strength in each group can be reported as follows: 22.2Mpa[3.38] for group one, 18.05Mpa[4.54] for group two, 24.5Mpa[5.69] for group three and the figure was 22.4Mpa[4.52] for group four. The statistical analysis demonstrated that Shear bond strength of new coarse diamond bur preparations were significantly [P<0.001] less than fine or used diamond burs. Used diamond burs of different durations can affect dentin bond strength of SE Bond self etch bonding system. Accurate type of bur and adhesive selection are essential in optimizing dentin adhesion to self-etching adhesives

[Effect of cavity liners on micro leakage of Cl V amalgam restorations]

There is no bonding between amalgams and restored cavity walls. Therefore, these restorations are prone to leakage despite the deposition of corrosion products. The aim of this in vitro study was to evaluate the effectiveness of three cavity liners in reducing micro leakage of class V amalgam restorations. Sixty-eight extracted intact human molar teeth were selected. Class V cavity preparations were performed in all teeth and they were randomly divided into four groups. Group one was used as a control group [no liner], and the rest were Varnish, Resin Cement [Panavia F], and Light-cured dentin bonding agent [Single Bond] groups. Or alloy amalgam was condensed into the prepared Cl V cavities. All teeth were immersed in distilled water at 37°C, for 24 hours. All restorations were subjected to 1000 thermal cycles at 5-55 degrees centigrade. For micro leakage test, all teeth were immersed in 0.5% Basic Fuchsine and sectioned. Dye penetrations were evaluated by stereomicroscope. The collected data were analyzed statistically by Kruskal-Wallis and Bonferroni test. The results showed significant differences between four groups [P< 0.05]. Control group showed the maximum and Panavia group revealed the minimum micro leakage. There was no significant difference between Panavia and Single Bond groups. On the other hand, no significant difference [P>0.008] was observed between occlusal and gingival margins in the control, Single Bond and Panavia groups. Although, the difference was statistically significant in varnish group [P=0.002]. When compared with control group, the dentin bonding agent, varnish and cement resin groups demonstrated significantly decreased micro leakage at the enamel margin [P=0.0001]. However, when compared with varnish and control group, the dentin bonding agent and cement resin groups demonstrated significantly decreased micro leakage at the cementum margin [P<0.008]. Findings of this investigation clearly demonstrate the advantage of using lining materials in amalgam restorations. Therefore, we can conclude that such materials may significantly increase the sealing ability and decrease the micro leakage in Class V amalgam restorations

influence of Iranian temporary components on shear bond strength of composite resin to deep dentin in a single bottle bonding system

There are controversies about the effect of eugenol containing cements on composite-dentin bond strength. This study was designed to evaluate the effect of eugenol containing temporary cements on shear bond strength of composite bonds to deep dentin when using Single Bond. In this in-vitro study, ninety extracted human third molars were sectioned horizontally at deep dentin and randomly divided in six groups after embedded into self cure acrylic material. Samples in five groups were covered with: Cavisol, Temband, and Zoliran with three different powder/liquid ratios of 10/2 gr., 10/3 gr., and 10/2 gr. respectively. The samples in group six were used as control and therefore they received no treatment. After elapse of one week, the temporary cements were removed mechanically from all samples in the first five groups. Only the samples in group five were cleaned by ethanol. All groups were pretreated with single bond and then composite cylinders were added. Debonding and shear bond strength was tested by using DARTEC universal testing machine. These data were analyzed using One-Way ANOVA and Duncan tests. The median shear bond strength were calculated for all six groups as follows: The values were 17.96 [ +/- 0.73], 15.06 [ +/- 0.78], 16.14 [ +/- 0.75], 13.76 [ +/- 0.66], 16.79 [ +/- 0.34], 18.12 [ +/- 36] Mega Paschal respectively. Significant group differences were found for all groups [P<0.001] except for first and sixth [P >0.05] as well as third and fifth groups. Temporary cements containing eugenol significantly reduced the shear bond strength of composite to deep dentin when using Single Bond

Shear bond strength between aged hybrid and new flowable composite resins using different bonding agents

Flowable composite is an appropriate choice for repairing old composite restorations because of its conservative nature, easy application and various colors available on the market, The aim of this study was to evaluate the shear bond strength between old hybrid and new flowable composite resins using Adhes, Single bond, Prompt L Pop and no dentin bonding agents. Eighty acrylic cylinders were fabricated with a standard cavity in the center. Tetric Ceram hybrid composite was placed in the cavities and cured. The cylinders were divided into two groups; one group was kept in water for one month and was then randomly divided into four subgroups. Dentin bonding agents were not used in the first subgroup but the selected bonding agents were applied to the cylinders in the other subgroups. Tetric Flow composite was placed on the primary composite. The same procedure was used for the second group except that the samples were not stored in water for one month. The shear bond strength was measured using a universal testing machine. The data were subjected to LSD variance and independent t-analysis. Shear bond strength values ranged from 33.27 to 16.62 MPa in the first group [in decreasing order: Adhes, Single-bond, control and Prompt L pop subgroups] and from 32.73 to 18.15 MPa in the second group [in decreasing order: Adhes, Single-bond, Prompt L pop and control subgroups]. In the first group, a significant difference was observed between the control versus Adhes and control versus Single bond subgroups and also between the Adhes and Prompt L pop and finally between the single bond and Prompt L pop subgroups. There was no significant difference between the control versus Prompt L pop and Adhes versus Single-bond subgroups. The results obtained in the 2nd group were similar to the first group. The shear bond strength between aged hybrid and new flowable composite resin may increase after application of dentin bonding agents

Comparative evaluation of different methods of strengthening in endodontically treated maxillary central incisors with thin root walls

The structural rehabilitation of a pulpless tooth is critically important to ensure a successful restorative outcome following endodontic treatment. A post and core is often indicated for the retention and reinforcement of the final restoration. But, the clinical situation is significantly challenging if the root exhibits immature development or there is a thin root wall that can compromise the prognosis for a long-term successful treatment. The purpose of this in vitro study was to evaluate different methods of intraradicular reinforcement in structurally compromised roots. In this experimental study, seventy two extracted intact maxillary central incisors with similar size, shape and root anatomy were selected. After root canal therapy in 60 teeth, an acrylic laboratory bur was used to thin the cervical area and simulate the thin dentinal walls of immature teeth. The preparation was performed through the palatal access and extended 5mm apical to CEJ. The remaining 12 teeth remained unprepared to serve as positive control group. Cases were randomly divided into six groups of 12 teeth each and restored as follows. In the 12 cervically unprepared teeth [positive controls] the composite resin with dentin bonding agent [DBA] was placed in access cavity and cured for 120 seconds. This technique was also applied to other groups when the access was restored with composite. In the second group, the access cavity was restored with composite only to the level of CEJ. In the third group the cervically prepared teeth were reinforced with cement resin [Enforce] and a prefabricated post was placed in 5mm apical to the CEJ. In the fourth group, the cervically prepared teeth were reinforced with composite resin and DBA by a clear plastic post. In the fifth group the cervically prepared teeth were reinforced with composite resin and dba and a cast post. In the sixth group the cervically prepared teeth were restored with composite resin and dba with a prefabricated post. All of the specimens were mounted by rubberized technique arid tested in the Instron universal testing machine. The fracture loads in samples were analyzed with ANOVA and Duncan tests with p<0.05 as the limit of significance., Significant differences in fracture resistance were observed between the first and second groups compared with others. The highest fracture resistance values were recorded for first group while the lowest were registered for the second group. Fracture resistance of the third, fourth and fifth groups had no significant statistical differences with others and fracture resistance of sixth group was the highest with significant difference [P<0.05]. From this study, it may be concluded that the use of a dba and a composite resin in thin-walled roots reinforces the immature teeth and facilitates the use of post

Effect of different adhesive systems on microleakage at the amalgam/composite interface

Ditching and marginal defects of amalgam restorations can cause microleakage, recurrent carries, pulp hypersensitivity and finally loss of the tooth. The complete replacement of large restoration is time consuming, difficult and may potentially damage the pulp. Therefore in cases were there is no sings of recurrent caries, composite repair can be chosen as an alternative. The purpose of this study was to compare the effect of different bonding agent application on microleakage between flowable composite and amalgam. Standard calss V amalgam preparations were prepared on 60 carries free premolars and the cavities were filled using amalgam. After 24 hours, a 1 mm cavity on the occlusal margin of the class V restorations was prepared and specimens were divided randomly into four treatment groups: First group was filled with flowable composite and Single bond. Second group was filled with flowable composite and SE bond. Third group was filled with flowable composite and Prompt-L-pop. Fourth group Was filled with flowable composite without denting bonding agent. Specimens were thermocycled and sealed with fingernail polish except the composite-amlagam interface, then immersed in basic fuchsine for 24 hours. Specimens were sectioned and microleakage was assessed. The data were analyzed using Kruskal-Wallis test and Mann-Whitney U test. The results indicated that dentin bonding agent is effective in decreasing the degree of microleakage in amalgam-flowable composite interface and also the clearfil SE bond was more effective than Prompt-L-pop. But there was no significant statistical difference in microleakage between SE bond and Single bond. The application of dentin bonding agents in repair of amalgam retoration using flowable composite decreases microleakage but more researches should be performed