An experimental teeth bleaching agent containing casein phosphopeptide-amorphous calcium phosphate.

OBJECTIVES: This study was aimed to obtain an experimental bleaching agent by adding casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) in order to eliminate the mineral loss on the tooth surface after bleaching and to evaluate the bleaching effectiveness. MATERIALS AND METHODS: In this study, experimental bleaching agents containing 1%, 3% CPP-ACP and without CPP-ACP were obtained. Bleaching effectiveness (color change), the effect of bleaching agents on mineral content (energy dispersive x-ray spectroscopy), surface morphology (scanning electron microscope), and surface hardness of enamel (Vicker's microhardness) before and after bleaching were evaluated. The obtained data were statistically analyzed. RESULTS: When the bleaching levels of the groups were compared, no statistically significant difference was observed between the control and 1% CPP-ACP groups (p > 0.05) while the addition of 3% CPP-ACP decreased significantly the effectiveness of the bleaching agent (p < 0.05). When the effects of experimental bleaching agents on surface hardness were examined, while the enamel surface hardness decreased statistically significantly after application in the control group (p < 0.05), no statistically significant change was observed in surface hardness after the application of 1% CPP-ACP containing bleaching agent (p > 0.05). However, a statistically significant increase was observed in surface hardness after the application of 3% CPP-ACP containing bleaching agent (p < 0.05). When the Ca and P ratio of the groups were compared, no statistically significant difference was observed between the control and 1% CPP-ACP groups (p > 0.05), while they increased significantly in 3% CPP-ACP group (p < 0.05). CONCLUSIONS: The addition of 1% CPP-ACP to the bleaching agent had positive effects on the mineral content and surface hardness of the enamel, and did not negatively affect the whitening effectiveness. CLINICAL SIGNIFICANCE: Adding CPP-ACP to the bleaching agent at appropriate concentrations can eliminate possible negative effects without compromising the effectiveness of the bleaching agent.

The influence of different placement techniques on the clinical success of bulk-fill resin composites placed in Class II cavities: a 4-year randomized controlled clinical study.

OBJECTIVE: The purpose of this double-blind and split-mouth randomized controlled clinical trial was to evaluate the clinical success of the placement technique (bulk-filling and incremental techniques) of a bulk-fill resin composite in Class II carious lesions. MATERIALS AND METHODS: Two different bulk-fill resin composites, X-tra fil (Voco) and Filtek Bulk Fill (3M ESPE), were used in the bulk-filling and incremental techniques for 20 patients. The study was carried out in 4 groups, with 20 restorations in each group. Restorations were appraised at baseline, 6-month, 2-year, and 4-year recall. World Dental Federation (FDI) and the US Public Health Service (USPHS) criteria were used in the evaluations. The Friedman, Kruskal-Wallis, and Mann-Whitney U tests were used for the statistical analysis. RESULTS: At the end of year 4, there was no loss of restoration in any group. According to the USPHS and FDI criteria, there was a difference in the baseline and 4-year in marginal adaptation and marginal discoloration of the restorations (P < 0.05). When Filtek-Bulk was placed as an incremental technique, there was a minor fracture in four restorations (P > 0.05). In addition, Filtek-Bulk showed a color change according to the results based on both the USPHS and FDI criteria (P < 0.05). The difference between the two placement techniques of each resin composite was not significant at the year 4 recall when all criteria were evaluated (P ˃ 0.05). CONCLUSIONS: The 4-year clinical success of the evaluated bulk-fill composites is not dependent on the placement technique used. CLINICAL RELEVANCE: This study can help clinicians choose which technique (bulk fill and incremental techniques) bulk-fill composites can be used. TRIAL REGISTRATION: US National Library of Medicine, www. CLINICALTRIALS: gov , ID: NCT04565860 Registered on 10/09/2020. Clinical Evaluation of Bulk-fill resin Composites in Class II Restorations.

Evaluation of six different one-step universal adhesive systems in terms of dentin bond strength, adhesive interface characterization, surface tension, contact angle, degree of conversion and solvent evaporation after immediate and delayed use.

OBJECTIVES: In this study, it was aimed to investigate the effects of different waiting periods on resin-dentin bond strength (BS), degree of conversion (DC), contact angle (CA), surface tension (ST), solvent evaporation (weight loss) and the characteristics of adhesive interfaces of the current six universal adhesive resins (ARs). MATERIALS AND METHODS: A total of 216 caries-free human lower third molar teeth were used. Composite resin restorations were performed by applying six universal ARs in etch-and-rinse and self-etch mode on standardized dentin surfaces after 0, 5, and 30 min waiting time. Then, a micro-shear BS test, SEM examination and characterization of the adhesive interface were performed. In addition, DC, CA, ST, solvent evaporation of all tested ARs were evaluated. RESULTS: The obtained data were statistically anaIyzed. The tested ARs did not show any statistical difference between 0 and 5 min evaluations in all parameters evaluated except for weight loss (p > 0.05). While the weight loss, ST and CA of all ARs increased in 30 min (p < 0.05), the BS, DC, thickness of the adhesive layer and the hybrid layer, resin tag length and number of resin tags varied according to the ARs used. When the ARs were used in etch-and-rinse mode, all the parameters evaluated also varied according to the AR used. Higher adhesive layer thickness and lower hybrid layer thickness were found in the self-etch mode (p < 0.05). CONCLUSIONS: All of the adhesives tested can be safely used up to 30 min. This could also prevent economical loss caused by waste adhesive material. CLINICAL SIGNIFICANCE: It is important to know how the bond strength, degree of conversion, adhesion, contact angle and surface tension properties of the adhesive resin waiting in the dispensing cup for a long time during clinical use are affected to make ideal restorations.

The effect of two different prophylaxis paste applying processes on color stability in-office bleaching: 24-month clinical follow-up.

OBJECTIVE: The purpose of this study was to examine the effect of applying two different prophylaxis pastes with various protocols on the degree of bleaching and color stability in the office bleaching process with a bleaching agent containing 40% hydrogen peroxide. MATERIAL AND METHOD: The 300 teeth of 15 (9 female, 6 male) patients were included in our study, and 5 different study groups were randomly formed. The bleaching process with Ultradent Opalescence Boost (Ultradent, South Jordan, USA) was performed according to the manufacturer's instructions. Two different prophylaxis pastes, Ultrapro (Ultradent, Cologne, Germany) and Cleanic (Kerr, Rastatt, Germany), were applied with protocols determined according to the groups. The effect on color stability at 6-, 12-, and 24-month follow-up was determined using the CIE L* a* b* color system. The changes in the parameters were analyzed using the one-way ANOVA, chi-square, and Tukey test (p > 0.05). RESULTS: The evaluation rate of the treatments was 100% at the end of 24 months. Control group 6-month ΔE (0-6) and 12-month ΔE (0-12) values were higher than 24-month ΔE (0-12) values. UU + UU, KC + KC, and UU group 6-month ΔE (0-6) values were higher than 12-month ΔE (0-12) values. In addition, 6-month ΔE (0-6) and 12-month ΔE (0-12) values were higher than 24-month ΔE (0-24) values. KC group 6-month ΔE (0-6) and 12-month ΔE (0-12) values were higher than 24-month ΔE (0-24) values. Control, UU + UU, KC + KC, UU, and KC group ΔE (1-6) values at 6 months were lower than 12-month ΔE (1-12) and 24-month ΔE (1-12) values in all groups. In addition, 12-month ΔE (1-12) values were lower than 24-month ΔE (1-24) values. According to the study data, there was no statistically significant difference between the groups according to the prophylaxis paste and prophylaxis procedure (p > 0.05). However, it was observed that whiteness decreased in all groups over time. CONCLUSIONS: Discoloration was observed at 6 months, 12 months, and 24 months after bleaching. However, at the end of 24 months, the tooth color was significantly whiter than the initial color. CLINICAL RELEVANCE: Pre-bleaching prophylaxis application and pre-bleaching and post-bleaching prophylaxis application have no effect on color stability.

The effect of five different universal adhesives on the clinical success of class I restorations: 24-month clinical follow-up.

OBJECTIVES: The aim of this study was to evaluate the 24-month clinical performance of universal adhesives on the restoration success of Class I carious lesions. MATERIALS AND METHODS: Five different universal adhesives (Gluma Bond Universal (GU), Clearfil Universal (CU), Prime&Bond Elect Universal (PU), All bond Universal (AU), and Single Bond Universal (SU)) were used in the self-etch and etch-and-rinse modes in 42 patients. The study was conducted with 10 groups, with 20 restorations in each group. The restorations were evaluated at baseline and during a 24-month recall using World Dental Federation (FDI) and the US Public Health Service (USPHS) criteria. The changes in the parameters were analyzed using the chi-square test. RESULTS: At the end of 24 months, there was no loss of restoration in any group. According to the USPHS, there was no difference in the baseline and 24-month clinical behavior of the restorations (P Ëƒ 0.05). However, according to the FDI, when adhesives were used in the self-etch mode, three adhesives (GU, SU, PU) showed marginal incompatibility, and one adhesive showed (GU) marginal discoloration between baseline and the 24-month follow-up evaluation (P < 0.05). There was no significant difference after 24 months between etch-and-rinse and self-etch groups according to the results based on both the USPHS and FDI criteria (P Ëƒ 0.05). CONCLUSIONS: The 24-month clinical performance of the evaluated universal adhesives depends on the adhesive strategy. CLINICAL RELEVANCE: This study helps clinicians to decide in which mode (etch-and-rinse or self-etch) universal adhesives can be safely used.

Effect of different gutta-percha solvents on the microtensile bond strength of various adhesive systems to pulp chamber dentin.

OBJECTIVES: The aim of this study was to evaluate the effect of different endodontic solvents on the microtensile bond strength (µTBS) of various adhesives to pulp chamber dentin. MATERIAL AND METHODS: A total of 120 human third molars were selected. Canals were prepared with the ProTaper Universal system and obturated. The access cavities were then restored with resin composite. After 1 week, a retreatment procedure was applied as follows: control, no solvent was applied to the pulp chamber and experimental groups, three different solvents (chloroform, eucalyptol, and orange oil) were applied to the pulp chamber for 2 min. The canal filling was removed and calcium hydroxide (Ca[OH]2) was placed into the canals. After 7 days, the Ca(OH)2 was removed from the canals and the canals were re-obturated. Teeth were then divided into three subgroups according to the adhesive used. The samples were restored with a nanohybrid resin composite using three different adhesives: Clearfil SE Bond (CSE), Adper Easy One (AEO), and Single Bond 2 (SB2). The samples were aged with thermocycling. Teeth were sectioned, and a total of 20 dentin sticks were obtained for each subgroup. µTBS testing was then performed. The debonded surfaces were evaluated using scanning electron microscopy (SEM) analysis. Data were analyzed using two-way ANOVA and Tukey's post hoc tests. RESULTS: Chloroform showed statistically lower mean µTBS values (14 ± 7.2 MPa) than control group did (19.2 ± 6.1 MPa) (p < 0.05). Orange oil (18.1 ± 6.3 MPa) and eucalyptol (16.9 ± 6.8 MPa) did not reduce the mean µTBS statistically (p > 0.05). Chloroform showed significantly lower bond strength for all adhesives (p < 0.05). Whereas orange oil did not reduce the mean µTBS values of all adhesive systems significantly (p > 0.05), eucalyptol reduced the µTBS values of all the groups, but the results were only statistically significant for SB2 (p < 0.05). CSE showed statistically higher bond strength (20.4 ± 6.8 MPa) than AEO (14.6 ± 5.3 MPa) and SB2 (16.3 ± 7.2 MPa) did (p < 0.05). There were no statistical differences between AEO and SB2 (p > 0.05). According to the SEM analysis of the debonded surfaces, adhesive failures were the most common type in all the groups, followed by mixed failures. CONCLUSIONS: While chloroform reduced the mean bond strength of the adhesive resins, orange oil did not affect the bond strength of the adhesives. The effect of eucalyptol on bond strength depended on the type of adhesive system. CLINICAL RELEVANCE: This study shows that endodontic solvents could affect the microtensile bond strength of adhesives to pulp chamber dentin.

The effect of various backfilling techniques on the fracture resistance of simulated immature teeth performed apical plug with Biodentine.

AIM: To evaluate the fracture resistance of simulated immature teeth that had been backfilled using different materials after using Biodentine as the apical plug material. DESIGN: Seventy-five single-rooted teeth were divided into five groups (n = 15). The 15 teeth in group 1 served as a negative control group and received no treatment. The remaining 60 teeth were instrumented to a #6 Peeso reamer to obtain a standard internal diameter of 1.5 mm. The apical 4 mm of 60 teeth was filled with Biodentine. The backfilling was then performed on each group as follows: group 2--no backfilling (positive control), group 3--gutta-percha, group 4--fiber post, and group 5--Biodentine. Specimens were then subjected to fracture testing. The force required to fracture each specimen was recorded, and the data were statistically analyzed. RESULTS: The mean fracture values of groups 1 and 4 were significantly higher than groups 2, 3, and 5 (P < 0.05). The values of groups 3 and 5 were significantly higher than group 2 (P < 0.05). CONCLUSIONS: The backfilling with fiber post after an apical Biodentine plug provided the highest fracture resistance among all experimental groups.

Dental age assessment for different climatic regions.

OBJECTIVE: The aim of this study was to evaluate the impact of several aspects of climate, such as temperature and altitude, on dental maturation. MATERIALS AND METHODS: The total sample consisted of 944 panoramic radiographs (473 Turkish children from Central Anatolia [228 girls and 245 boys] and 471 Turkish children from Eastern Anatolia [222 girls and 249 boys]). The children aged between 7.0 and 14.9 years. The radiographs were randomly selected from 2 cities in Turkey, Kayseri and Erzurum. Independent t tests and paired t tests were performed to compare sex, location, and age to determine the relationships between tooth developments. RESULTS: The Central Anatolian children were approximately 0.2 to 3.0 years more advanced in dental maturity than the Eastern Anatolian subjects. CONCLUSIONS: The development standards proposed by Demirjian are affected by climatic factors. However, further research and detailed information to gather data are needed.

Use of cone-beam computed tomography to evaluate root and canal morphology of mandibular first and second molars in Turkish individuals.

OBJECTIVE: The aim of this study was to investigate the root and canal morphology of mandibular first and second molars in a Turkish population by using cone beam computed tomography (CBCT). STUDY DESIGN: CBCT images of mandibular first (n = 823) and second molar (n = 925) teeth from 605 Turkish patients were analyzed. The root canal configurations were classified according to the method of Vertucci. RESULTS: The majority of mandibular molars (95.8% of first molars, 85.4% of second molars) had two separate roots; however, three roots were identified in 2.06% of first molars and 3.45% of second molars. C-shaped canals occurred 0.85% of first molars and 4.1% of second molars. Three canals were found in 79.9% of first molars and 72.8% of second molars. Most distal roots had a simple type I configuration, whereas mesial roots had more complex canal systems, with more than one canal. The most common root morphology of first and second molars is the two rooted morphology with three canals. Both the mesial and distal roots showed wide variations in canal anatomy with type IV and type I canal configuration predominating in the mesial and distal roots, respectively. CONCLUSION: Vertucci type I and IV canal configurations were the most prevalent in the distal and mesial roots, respectively, of both the mandibular first and second permanent molar teeth.

Three-year clinical performance of two indirect composite inlays compared to direct composite restorations.

OBJECTIVE: Despite the incremental build-up of resin composite restorations, their polymerization shrinkage during curing presents a serious problem. Indirect composite resin systems represent an alternative in overcoming some of the deficiencies of direct composite restorations. The hypothesis of the present study states that the clinical performance of restorations may be affected by different generation and application techniques. STUDY DESIGN: Sixty restorations (20 DI system (Coltène/Whaledent AG, Altstätten, Switzerland) composite inlays, 20 Tescera ATL system (BISCO Inc. Schaumburg, Illinois, USA) composite inlays, and 20 direct composites) were applied to premolar teeth in 49 patients. Restorations were clinically evaluated by two examiners. Data were analyzed using the Kruskal-Wallis, Mann-Whitney U, Wilcoxon Signed Ranks, and X2 tests. RESULTS: The Tescera ATL system performed significantly better than both direct composite restorations (p<0.001) and DI system (p<0.05). CONCLUSION: Within the limitations of this 3-year clinical study, indirect resin restorations showed better scores than direct restorations. In addition, the Tescera ATL system was found to be more successful than the DI system and direct composite restorations.

Evaluation of drug release, monomer conversion and surface properties of resin composites containing chlorhexidine-loaded mesoporous and nonporous hydroxyapatite nanocarriers.

The aim of this study was to evaluate drug release, degree of conversion (DC), and surface properties of resin composites containing chlorhexidine (CHX)-loaded mesoporous (mHAP) and nonporous hydroxyapatite (HAP) nanocarrier. CHX loaded mHAP and HAP, or CHX without nanocarrier was added into the resin composite in 1% and 5% concentrations. After characterization of experimental materials with XRD, EDX, FT-IR, and SEM, the CHX release on the 1st, 7th, 30th, and 120th days were evaluated by UV-vis spectroscopy. DC, surface roughness, and surface hardness of the samples were also evaluated. The data was statistically analyzed. While mHAP groups released significantly higher CHX on the 30th day (p < .05), there was no statistically significant difference between the HAP and mHAP groups on the 120th day (p > .05). DCs of all groups were similar (p > .05). While mHAP and HAP groups containing 5% CHX showed significantly higher roughness than the other groups (p < .05), no statistically significant difference was observed between the other groups (p > .05). The 1% and 5% CHX groups without nanocarrier showed significantly lower surface hardness (p < .05). However, no statistically significant difference was observed between the other groups in terms of surface hardness (p > .05). A controlled CHX release was achieved by mHAP and HAP nanocarriers for 120 days. The nanocarrier addition up to 5% did not negatively affect the DC and the surface hardness which is one of the surface properties of the resin composites. Although the addition of 5% nanocarrier to the resin composite increased the surface roughness, while adding 1% of these nanocarriers did not change.

Effect of different coronal restorations on the fracture resistance of teeth with simulated regenerative endodontic treatment: An in vitro study.

This study investigated the effect of different coronal restorations on the fracture resistance (FR) of immature teeth with simulated regenerative endodontic treatment. A total of 120 lower premolars were divided into eight groups. Except for negative control, the root canals were instrumented with rotary files and Peeso reamers. Fifteen instrumented teeth were acted as positive control (unrestorated). In the remaining 90 teeth, regenerative endodontic treatment procedures were performed. Ninety teeth were randomly divided into 6 groups according to coronal restoration type; Filtek Z550, Filtek Bulk fill Restorative (FBR), SDR+Filtek Z550, EverX+Filtek Z550, Ribbond+FBR and Ribbond+SDR+Filtek Z550. After thermal ageing, the restorated teeth were subjected to vertical loading force. FR values was obtained as follows: Negative control > Ribbond+FBR = Ribbond+SDR+Filtek Z550 > Filtek Z550 = FBR =SDR+Filtek Z550 = EverX+Filtek Z550 > Positive control, (P < 0.05). The use of Ribbond in combination with composite resin enhanced the FR of teeth.

Discoloration Behavior of Resin Cements Containing Different Photoinitiators.

The purpose of this study was to evaluate the sorption, solubility, and color stability of amine-free conventional light-cure and dual-cure resin cements and an amine-containing self-adhesive dual-cure resin cement. Sixty specimens were prepared using a light-cure resin cement (Variolink Esthetic LC, Ivoclar Vivadent; VE-LC), a dual-cure resin cement (Variolink Esthetic DC, Ivoclar Vivadent; VE-DC), and a self-adhesive dual-cure resin cement (RelyX U200, 3M ESPE; RXU200). The water sorption and solubility were tested by immersing the specimens in distilled water for 7 days. Kruskal-Wallis test was applied to the data. ΔE values of 1-day and 7-day immersion in black tea were analyzed using one-way analysis of variance followed by Tukey honest significant difference test (n = 10). There was no statistically significant difference among the groups in terms of sorption and solubility. The mean ΔE of RXU200 for the 0/1 and 0/7 days were found to be significantly lower than that of VE-LC and VE-DC (P < .05). ΔE values of the VE-LC and VE-DC groups did not reveal statistical difference. It should be taken into account that discoloration of resin cements remains a problem even with amine-free products.

Investigation of ellagic acid rich-berry extracts directed silver nanoparticles synthesis and their antimicrobial properties with potential mechanisms towards Enterococcus faecalis and Candida albicans.

The essential goals of this present study are to elucidate the formation mechanism of ellagic acid rich-blackberry, BBE, (Rubus fruticosus L.) and raspberry, RBE, (Rubus idaeus L.) extracts directed silver nanoparticles and to investigate thier antimicrobial properties towards model dental pathogens E. faecalis and C. albicans compared to BBE, RBE, NaOCl, CHX and EDTA. Both %5 w/w of BBE and RBE reacted with 5 mM Ag + ions at room temperature (25 °C) under mild-stirring, the formation of BBE and RBE directed b@Ag NP and r@Ag NP was monitored over time by using an Uv-vis spectrophotometer. Both b@Ag and r@Ag NPs were also complementarily characterized with SEM and FT-IR. In terms of the antimicrobial studies, b@Ag NP, r@Ag NP, %5 BBE and RBE, 5 mM AgNO3, %5 NaOCl, %1,5 CHX and %15 EDTA were separately incubated with E. faecalis and C. albicans suspensions. The results were evaluated with student t-test using GraphPad Prism 8.0.1 statistical software (P < 0.05). While formation of b@Ag NP was confirmed with characteristic absorbance at ~435 nm in 20 min (min) of incubation, r@Ag NP did not give absorbance till 80 min owing to concentration of ellagic acid acted as a reducing and stabilizng agent for formation of the Ag NPs. Intrestingly, 50 ppm r@Ag NP inactivated ∼89% and ∼99% of E. faecalis and C. albicans cell, respectively, ∼25% and ∼40% cell inactivations for E. faecalis and C. albicans were observed respectively with 50 ppm b@Ag NP. We showed that 50 ppm r@Ag NP has effective antimicrobial property as much as mostly used %5 NaOCl and %1,5 CHX solutions.

A deep learning approach to dental restoration classification from bitewing and periapical radiographs.

OBJECTIVE: The aim of this study was to examine the success of deep learning-based convolutional neural networks (CNN) in the detection and differentiation of amalgam, composite resin, and metal-ceramic restorations from bitewing and periapical radiographs. METHOD AND MATERIALS: Five hundred and fifty bitewing and periapical radiographs were used. Eighty percent of the images were used for training, and 20% were left for testing. Twenty percent of the images allocated for training were then used for validation during learning. The image classification model was based on the application of CNN. The model used Resnet34 architecture, which is pre-trained on the ImageNet dataset. Average sensitivity, receiver operating characteristic (ROC) curve, and area under the curve (AUC) were calculated for performance evaluation of the model. RESULTS: The model training loss was 0.13, and the validation loss was 0.63. The independent test group result was 0.67. Amalgam AUC was 0.95, composite AUC was 0.95, and metal-ceramic AUC was 1.00. The average AUC was 0.97. The false positive rate in the validation set was 18, the false negative rate was 18, the true positive rate was 60, and the true negative rate was 138. The true positive rate was 0.82 for amalgam, 0.75 for composite, and 0.73 for metal-ceramic. CONCLUSION: Deep learning-based CNNs from periapical and bitewing radiographs appear to be a promising technique for the detection and differentiation of restorations.

Micro-computed Tomographic Assessment of the Residual Filling Volume, Apical Transportation, and Crack Formation after Retreatment with Reciproc and Reciproc Blue Systems in Curved Root Canals.

INTRODUCTION: The purpose of the present study was to evaluate the remaining root canal filling material, apical transportation, and crack formation after retreatment with M-Wire Reciproc (VDW GmbH, Munich, Germany) and Reciproc Blue (VDW GmbH) systems in curved root canals. METHODS: Twenty-six mandibular first and second molars with mesial roots that had 2 separate canals with angles between 20° and 40° were selected for this study. The root canals were prepared with M-Wire Reciproc size 25 instruments (VDW GmbH), and they were filled with gutta-percha and AH Plus sealer (Dentsply Sirona, Tulsa, OK). The samples were randomly divided into 2 groups (n = 13 each) according to the retreatment system used: an M-Wire Reciproc group and a Reciproc Blue group. The canals were retreated up to instrument size 25 and then to size 40 in both groups. After the retreatment procedures, the residual filling material volume, apical transportation, and crack formation were assessed using micro-computed tomographic imaging. RESULTS: There were no significant differences between the groups in the amount of residual filling material (P > .05). The apical canal transportation values were significantly higher in the M-Wire Reciproc group than in the Reciproc Blue group at 1 mm. No significant differences were observed between the groups at any of the other levels with regard to apical transportation (P > .05) The new uncompleted and completed cracks were observed in both groups. There were no statistically significant differences between the groups in terms of crack and fracture formation (P > .05). CONCLUSIONS: The Reciproc Blue system is as effective as the M-Wire Reciproc system in terms of the retreatment of the curved mesial roots of mandibular molars. However, the formation of new uncompleted and completed cracks was found during the retreatment procedures.

Influence of a short-time antioxidant application on the dentin bond strength after intracoronal bleaching.

This study evaluated the effects of an antioxidant application on the compromised bond strength of an adhesive to dentin bleached with 35% hydrogen peroxide. The dentin surfaces of the pulp chambers of 70 human third molars were ground, and the specimens were assigned randomly into seven groups, as follows: (a) control (unbleached); (b) bleached for 45 min, bonded immediately; (c) bleached for 45 min, treated with sodium ascorbate (SA) for 2 min, and bonded; (d) bleached for 45 min, bonded after 2 weeks; (e) bleached for 12 days, bonded immediately; (f) bleached for 12 days, treated with SA for 10 min, and bonded; and (g) bleached for 12 days, bonded after 2 weeks. In each group, the multimode adhesive was applied in etch-and-rinse and self-etch modes. The dentin surfaces were covered with a resin-based composite, and the bonded specimens were sectioned to produce composite-dentin sticks. The sticks were attached to a testing machine and subjected to a tensile force, and the representative specimens were examined via scanning electron microscopy. The bond strength was not affected by the application period of the bleaching agent. Both bleaching treatments significantly reduced the bond strength to the dentin in the self-etch or etch-and-rinse mode when compared with the control group. The bond strengths returned to normal levels with the SA applications or by waiting 2 weeks, regardless of the application period of the bleaching gel. The adhesive revealed a higher bond strength in the etch-and-rinse mode than in the self-etch mode.

The Effect of Different Cavity Designs and Temporary Filling Materials on the Fracture Resistance of Upper Premolars.

INTRODUCTION: The aim of this study was to compare the fracture resistance of upper premolars undergoing root canal treatment that had been temporarily restored with 4 different temporary filling materials. METHODS: This study was based on 120 extracted upper premolars. Eight teeth were left intact and served as the negative control group. Mesio-occluso-distal cavities with 2 different designs were prepared for the rest of the teeth (for group 1 a width of one third of the intercuspal distance and for group 2 a width of two thirds of the intercuspal distance). Then, the endodontic access cavities were prepared, and the root canals instrumented with Revo-S rotary files (MicroMega, Besancon, France). Thereafter, a total of 16 teeth consisting of 8 each from group 1 and group 2 served as the positive control group and did not have any temporary filling material. The teeth were randomly divided into 4 subgroups (n = 12) according to the temporary filling material: Cavit G (3M ESPE, St Paul, MN), Coltosol F (Coltène/Whaledent AG, Altstätten, Switzerland), Intermediate Restorative Material (Dentsply Sirona, Konstanz, Germany), or DiaTemp (DiaDent Europe BV, Almere, Netherlands). Each specimen was then subjected to a fracture resistance test using a universal testing machine until the fracture occurred. The force required to fracture each specimen was recorded, and the data were statistically analyzed. RESULTS: The negative control group showed the highest fracture resistance values compared with the other groups, whereas the positive control groups showed the lowest fracture resistance values. There were no statistically significant differences in the fracture resistance of upper premolar teeth undergoing root canal treatment among Cavit G, Intermediate Restorative Material, Coltosol F, and DiaTemp, regardless of the cavity width (P > .05). CONCLUSIONS: The cavity design was found to be an effective factor on the fracture resistance of upper premolar teeth undergoing root canal treatment. The temporary filling materials tested did not affect the fracture resistance.

The Effect of Cryotherapy Application on the Success Rate of Inferior Alveolar Nerve Block in Patients with Symptomatic Irreversible Pulpitis.

INTRODUCTION: This randomized clinical trial assessed the effect of preoperative intraoral cryotherapy application on the success rate of inferior alveolar nerve blocks (IANBs) in patients with symptomatic irreversible pulpitis (SIP). METHODS: One hundred four patients with SIP were randomly distributed into 2 groups: control and cryotherapy groups. In the control group, patients received an IANB injection with 2% lidocaine. In the cryotherapy group, intraoral cryotherapy application was performed for 5 minutes after the IANB. Endodontic therapy was then conducted 15 minutes after the IANB injection. If the patients reported moderate or severe pain during the procedure, the IANB was defined as "unsuccessful," and a supplementary injection was administered. RESULTS: All patients reported profound lip numbness. The overall success rate for the IANBs was 43.3%. In the cryotherapy group, the success rate of the IANBs was 55.8%, whereas in the control group it was 30.8% (P < .05). CONCLUSIONS: Intraoral cryotherapy application increased the success rate of IANBs in mandibular molar teeth with SIP. However, supplemental anesthesia techniques may still be required to provide profound pulpal anesthesia in many cases.

Bonding performance of universal adhesives on composite repairs, with or without silane application.

AIM: This study aims to investigate the adhesive performance of three different universal adhesives to repair aged composite restorations, with or without the application of silane. MATERIALS AND METHODS: A hundred and twenty resin composite samples were prepared, aged and randomly divided into 6 main Groups (single bond universal [SBU], All-Bond Universal [ABU], Futurabond U, Clearfil Tri-S Bond, Single Bond 2, and Clearfil SE Bond) and 2 subgroups (with or without silane). A microhybrid composite resin was placed on the aged composite surfaces and light cured. After a micro-shear bonding test, the fracture surfaces were examined under the scanning electron microscopy. Statistical analysis was performed using two-way ANOVA and Tukey's post hoc tests. RESULTS: Among all the universal adhesives, SBU showed the highest bond strength values compared to the other two universal adhesives when used with and without silane (P > 0.05). Between ABU and Futurabond U, no significant difference was observed with silane (P > 0.05) and without silane (P > 0.05). Among conventional adhesives, there was no statistically significant difference (P > 0.05) both with and without silane. CONCLUSION: Within the limitations of this study, while SBU can be safely used with and without the application of silane, Futurabond U cannot be used without silane.