The effect of different ratios of nano-sized hydroxyapatite fillers on the micro-tensile bond strength of an adhesive resin.

The purpose of this study was to evaluate the micro-tensile bond strength (µTBS) of dentin bonding agents containing different ratios of nano-sized hydroxyapatite fillers (HA). X-ray diffraction analysis was used for characterization, and scanning electron microscope (SEM) analysis was used to determine the HA particle size after that HA were mixed a bonding agents without filler. Dentin bonding agents were divided into four groups according to addition of different ratios of nano-sized hydroxyapatite fillers as 2% HA, 5% HA, 7% HA, and no-filler control group. The teeth (n = 32) were sectioned with a low-speed diamond blade under water cooling to expose the mid-coronal dentin. Following the bonding application, restorations were applied incrementally. Each tooth was cut on the x and y axis, and each specimen was fixed to a testing device and stressed until failure occurred. The debonded specimens were examined under 250× magnification without a coating layer at 2.00 kV using a SEM to determine failure patterns. µTBS data were analyzed using a anova and Tukey's post hoc test. The failure mode data were analyzed using the Chi-Square test. The maximum mean value of µTBS was in the 7% HA group, while the minimum mean value of µTBS was observed in the control group. 7% HA group was statistically significant and higher than other groups while there were no significant differences between the control, 2% HA, and 5% HA groups. According to SEM analysis, fracture analysis revealed that the mixed fracture type was seen more often than the other fracture types. The particle size and amount of HA fillers added to the adhesive resin seem to affect the success of the bond strength to the dentin. Adding different ratio nano-sized HA fillers to the adhesive resin contributed positively to the immediate µTBS values in the dentin.

Spectrophotometric color analysis of maxillary permanent central incisors in a pediatric population: a preliminary study.

BACKGROUND: Although several studies have reported the color distribution of maxillary central incisors and the effects of age and gender, a reliable database of the color of newly erupted teeth with open apices and the effect of the root development stage on tooth color shades do not currently exist. AIM: The purpose of this in vivo study was to perform a spectrophotometric color analysis of maxillary permanent central incisors based on apical developmental stage, age, and gender groups. DESIGN: A total of 734 maxillary permanent central incisors from 367 children aged 7-18 years who have fully erupted, intact, unrestored, vital right and left maxillary central incisors were evaluated. The patients were divided into nine groups, according to the root development stage and age. Digital images were quantified by non-contact spectrophotometry to determine the tooth color. Each tooth's color shade and L*, a*, and b* values were recorded. The L*, a*, and b* values were analyzed statistically with a multivariate analysis of variance test, and the color shades were analyzed with chi-square tests at the α = 0.05 level. RESULTS: The most common general tooth shade, for both genders, was A2. A statistically significant difference was found between the 7- to 12-year-old and 13- to 18-year-old age groups in the general tooth shade and its L* value in the overall, cervical, middle, and incisal sites (P < 0.05). CONCLUSION: There is a strong relationship between the apical developmental stages of the teeth and the L* values.

Evaluation of the remineralization capacity of CPP-ACP containing fluoride varnish by different quantitative methods.

OBJECTIVE: The aim of this study was to evaluate the efficacy of CPP-ACP containing fluoride varnish for remineralizing white spot lesions (WSLs) with four different quantitative methods. MATERIAL AND METHODS: Four windows (3x3 mm) were created on the enamel surfaces of bovine incisor teeth. A control window was covered with nail varnish, and WSLs were created on the other windows (after demineralization, first week and fourth week) in acidified gel system. The test material (MI Varnish) was applied on the demineralized areas, and the treated enamel samples were stored in artificial saliva. At the fourth week, the enamel surfaces were tested by surface microhardness (SMH), quantitative light-induced fluorescence-digital (QLF-D), energy-dispersive spectroscopy (EDS) and laser fluorescence (LF pen). The data were statistically analyzed (α=0.05). RESULTS: While the LF pen measurements showed significant differences at baseline, after demineralization, and after the one-week remineralization period (p<0.05), the difference between the 1- and 4-week was not significant (p>0.05). With regards to the SMH and QLF-D analyses, statistically significant differences were found among all the phases (p<0.05). After the 1- and 4-week treatment periods, the calcium (Ca) and phosphate (P) concentrations and Ca/P ratio were higher compared to those of the demineralization surfaces (p<0.05). CONCLUSION: CPP-ACP containing fluoride varnish provides remineralization of WSLs after a single application and seems suitable for clinical use.

Evaluation of the remineralization capacity of CPP-ACP containing fluoride varnish by different quantitative methods

ABSTRACT Objective The aim of this study was to evaluate the efficacy of CPP-ACP containing fluoride varnish for remineralizing white spot lesions (WSLs) with four different quantitative methods. Material and Methods Four windows (3x3 mm) were created on the enamel surfaces of bovine incisor teeth. A control window was covered with nail varnish, and WSLs were created on the other windows (after demineralization, first week and fourth week) in acidified gel system. The test material (MI Varnish) was applied on the demineralized areas, and the treated enamel samples were stored in artificial saliva. At the fourth week, the enamel surfaces were tested by surface microhardness (SMH), quantitative light-induced fluorescence-digital (QLF-D), energy-dispersive spectroscopy (EDS) and laser fluorescence (LF pen). The data were statistically analyzed (α=0.05). Results While the LF pen measurements showed significant differences at baseline, after demineralization, and after the one-week remineralization period (p<0.05), the difference between the 1- and 4-week was not significant (p>0.05). With regards to the SMH and QLF-D analyses, statistically significant differences were found among all the phases (p<0.05). After the 1- and 4-week treatment periods, the calcium (Ca) and phosphate (P) concentrations and Ca/P ratio were higher compared to those of the demineralization surfaces (p<0.05). Conclusion CPP-ACP containing fluoride varnish provides remineralization of WSLs after a single application and seems suitable for clinical use.

Effects of pulp capping materials on fracture resistance of Class II composite restorations.

OBJECTIVE: The aim of this study was to investigate the effect of cavity design and the type of pulp capping materials on the fracture resistance of Class II composite restorations. MATERIALS AND METHODS: Sixty freshly extracted, sound molar teeth were selected for the study. A dovetail cavity on the mesio-occlusal and a slot cavity on disto-occlusal surfaces of each tooth were prepared, and the teeth were divided 4 groups which one of them as a control group. The pulp capping materials (TheraCal LC, Calcimol LC, Dycal) applied on pulpo-axial wall of each cavity, and the restoration was completed with composite resin. The teeth were subjected to a compressive load in a universal mechanical testing machine. The surfaces of the tooth and restoration were examined under a stereomicroscope. The data were analyzed using factorial analysis of variance and Tukey's test. RESULTS: For pulp capping materials, the highest fracture load (931.15 ± 203.81 N) and the lowest fracture load (832.28 ± 245.75 N) were calculated for Control and Dycal group, respectively. However, there were no statistically significant differences among all groups (P > 0.05). The fracture load of the dovetail groups was significantly higher than those of the slot cavity groups (P < 0.05). CONCLUSION: Dovetail cavity design shows better fracture resistance in Class II composite restorations, independent of used or not used pulp capping materials.

Comparison of bleaching efficacy of two bleaching agents on teeth discoloured by different antibiotic combinations used in revascularization.

OBJECTIVES: To investigate the whitening effects of different bleaching agents on teeth discoloured by different antibiotic combinations of ciprofloxacin and metronidazole with minocycline, doxycycline, amoxicillin or cefaclor. MATERIALS AND METHODS: Forty extracted bovine incisors were collected and discoloured with triple antibiotic pastes (TAP) with minocycline, doxycycline, amoxicillin and cefaclor throughout 30 days. The specimens were then randomly divided into two subgroups and each group received different bleaching materials: 35% hydrogen peroxide and sodium perborate. Spectrophotometric measurements were obtained on the buccal surfaces of the crown, firstly in the beginning, then on the 4th, 8th and 12th days after the placement of the bleaching materials. The acceptability threshold was set to 3.5. The ∆E values were calculated and the data was analysed using the repeated measures analysis of variance (P = .05). RESULTS: All the test groups induced colour changes exceeding the acceptability threshold 30 days after the antibiotic pastes were placed. The 35% hydrogen peroxide was more effective than sodium perborate in the whitening of discoloured teeth by antibiotic pastes (P = .001). The whitening effect after the 8th and 12th days was significantly more than after 4 days of treatment (P <.001). The discolouration caused by the TAP with minocycline and cefaclor showed greater whitening compared to the TAP with doxycycline and amoxicillin groups (P <.05). CONCLUSIONS: The whitening treatment effect of 35% hydrogen peroxide on teeth discoloured by antibiotic pastes seems to have significantly outperformed the sodium perborate treatment. Both bleaching agents were allowed to bleach the teeth gradually each day and the effects on the 8th and 12th days were superior to the one on the 4th day. CLINICAL RELEVANCE: The use of 35% hydrogen peroxide could be advantageous to bleach the teeth discoloured with antibiotic pastes compared to sodium perborate.

Spectrophotometric analysis of crown discoloration induced by various antibiotic pastes used in revascularization.

INTRODUCTION: Antibiotic pastes are used for disinfection in regenerative endodontic procedures. This study evaluated the crown discoloration induced by various antibiotic pastes including the mixture of metronidazole and ciprofloxacin with minocycline, doxycycline, amoxicillin, or cefaclor. METHODS: Seventy extracted bovine incisors were sectioned to obtain a standardized root length of 10 mm above the facial cementoenamel junction. After pulp tissue removal, irrigation with sodium hypochlorite and the placement of temporary filling material and cotton pellet were performed from the apical aspect. The specimens were then randomly divided into 7 groups (n = 10 for each group), and each group received the following antibiotic paste fillings: no filling (control group), calcium hydroxide, double antibiotic paste (DAP), triple antibiotic paste (TAP) with minocycline, TAP with doxycycline, TAP with amoxicillin, and TAP with cefaclor. Spectrophotometric readings were obtained on the buccal surfaces of the crown on day 1 to week 3 after filling, and the ΔE value was calculated. Data were analyzed with 2-way analysis of variance and the Tukey post hoc tests (P = .05), and the human perceptibility threshold was set to 3.7. RESULTS: TAP with minocycline, doxycycline, and cefaclor induced more coronal discoloration compared with the control group (P < .05). The control, calcium hydroxide, and DAP groups showed no color changes exceeding the perceptibility threshold at all time points. CONCLUSIONS: The results indicated that all antibiotic pastes, except DAP, induced crown discoloration.