ER Mode Research Articles

Comparing Various Resin Luting Cement Systems in Different Etching Modes Through Bond Durability and Morphological Features.

This study aimed to investigate bond performance of various resin luting cement (RLC) systems on enamel and dentin in different etching modes and to compare the RLC-tooth interface morphology using scanning electron microscopy (SEM). The self-adhesive RLC systems used in combination with universal adhesives were as follows: Scotchbond Universal Adhesive Plus + RelyX Universal (3M Oral Care) and Clearfil Universal Bond Quick ER + SA Luting Multi (Kuraray Noritake Dental). These RLC systems were also used alone as self-adhesive RLC systems without universal adhesives (self-adhesive mode). The conventional RLC systems for comparison materials were as follows: BeautiBond Xtream + ResiCem EX (Shofu) and Tooth Primer + Panavia V5 (Kuraray Noritake Dental). Twelve specimens were prepared for each group to measure shear bond strength (SBS) in different etching modes. A stainless-steel rod was used as a substitute for indirect restorations. Bonded specimens were allocated to baseline (stored for 24 hours) and artificially aged (thermocycling [TC] for 10,000 cycles) groups. Representative treated tooth surfaces and RLC-tooth interfaces were observed using SEM. Three-way analysis of variance (ANOVA) revealed that all the factors (etching mode, storage period, and RLC system) had a significant influence on the enamel SBS values (p<0.05). Enamel SBS was significantly higher in etch-&-rinse (ER) mode than in self-etch (SE) mode, regardless of RLC system or storage period. Three-way ANOVA showed that all the factors had a significant influence on the dentin SBS values (p<0.001). Most RLC systems showed significantly higher dentin SBS in SE mode than in ER mode, regardless of storage period. However, the combination with Scotchbond Universal Adhesive Plus and RelyX Universal showed no significant difference in SBS values between etching modes at the baseline and showed a significantly higher SBS value in ER mode than in SE mode after TC. The self-adhesive RLC systems with universal adhesives tended to show higher enamel and dentin bond performance than the self-adhesive RLC systems alone. The morphology of treated tooth surfaces and resin cement-tooth interfaces were dependent on the RLC system and etching mode used. The RLC systems with primer application showed a thin, high-density layer above the intact dentin in both etching modes, suggesting chemical interaction.

A Comparative Evaluation of Shear Bond Strength of Embrace WetbondTM Pit and Fissure Sealant with or without the Use of a Universal Dental Adhesive System [ScotchbondTM Universal Adhesive] Using Different Bonding Protocols: A Multiparametric In Vitro Study.

To evaluate and compare the shear bond strength (SBS) of Embrace WetBondTM (EWS) Pit and Fissure Sealant (PF sealants) with or without the use of a universal dental adhesive system ScotchbondTM Universal Adhesive (SBU) using different bonding and curing protocols and to assess and compare the mode of failure as determined by visualization of the fractured surfaces of the test specimens after shear testing under an optical microscope at a magnification of 20×. A total of 85 samples were prepared for testing SBS on enamel on caries-free, extracted permanent human molars. The specimens were randomly divided into five groups based on different bonding and curing protocols. A knife-edge blade in a universal testing machine was used to perform the SBS test with a crosshead speed of 1 mm/minute. Then the mode of failure was assessed. Results were analyzed using a one-way analysis of variance with Tukey's post hoc test and Chi-squared test. A probability value 0.05 (p ≤ 0.01) was regarded as significant. ScotchbondTM Universal Adhesive (SBU) in total-etch (TE) mode/etch-and-rinse (ER) mode with individual light curing of the sealant and adhesive showed the highest SBS to enamel (5.40 ± 2.51 MPa). A predominance of cohesive mode of failure was observed for all the test groups. Embrace WetBondTM (EWS) PF sealants with SBU in the ER mode of application, with either curing mode, can be used as an alternative to a conventional technique for sealant placement for improving interfacial bond strength to enhance sealant retention and efficacy. Embrace WetBondTM (EWS) PF sealants with SBU in the ER mode of application can be used as an alternative to a conventional technique for sealant placement for improving interfacial bond strength. Swathy SR, Naidu J. A Comparative Evaluation of Shear Bond Strength of Embrace WetbondTM Pit and Fissure Sealant with or without the Use of a Universal Dental Adhesive System [ScotchbondTM Universal Adhesive] Using Different Bonding Protocols: A Multiparametric In Vitro Study. Int J Clin Pediatr Dent 2023;16(1):48-53.

Efficacy of different Er:YAG laser-activated photoacoustic streaming modes compared to passive ultrasonic irrigation in the retreatment of curved root canals.

To evaluate the efficacy of passive ultrasonic irrigation (PUI) and super short pulse (SSP) and shock wave-enhanced emission photoacoustic streaming (SWEEPS) modes of Er:YAG laser-activated irrigation (LAI) with two different laser tips, in removing filling remnants after conventional retreatment in severely curved root canals. The study sample consisted of 40 extracted molars with curved mesiobuccal root canals. The canals were instrumented with ProTaper Next and filled with an epoxy resin-based sealer and gutta-percha using continuous wave vertical compaction and warm injection back-filling. After retreatment with ProTaper Universal Retreatment system and sodium hypochlorite (NaOCl), all samples were randomly divided into four groups (n = 10) according to the final irrigation technique: PUI, LAI/SSP, SWEEPS/flat-tip, and SWEEPS/radial-tip, using 6mL of 3% NaOCl for an activation time of 3 × 30s. The samples were subjected to micro-CT scans after root canal filling, retreatment, and final irrigation. The filling material volume and percentage reduction were calculated. All tested irrigation techniques were successful in the elimination of the filling remnants after the retreatment (p < 0.001). The LAI/SSP group showed a higher reduction rate than the SWEEPS/flat-tip group (p = 0.032). No significant differences were found between the other groups (p > 0.05). All tested techniques improved the removal of filling material during retreatment in curved canals. LAI/SSP showed slightly better results than other techniques. The study highlights the need for additional activated irrigation after the retreatment of curved root canals. The choice between PUI and LAI is not decisive for success.

Shear Bond Strength of a Multi-Mode Universal Adhesive Containing Hydroxy-Apatite Nanoparticles to Dentin (In vitro study)

Aim: To evaluate the effect of addition of Hydroxyl-Apatite nanoparticles to a commercial universal adhesive on sheer-bond-strength to dentin using two application modes, immediately and after thermocycling. Methods: A-commercial UA was used for bonding composite-resin to dentin and considered as control. 10% of HAp were prepared and added to the commercial UA and considered as experimental. 88-freshly extracted sound human premolar teeth were sectioned to expose mid-coronal-dentin. Samples were y divided into: control and experimental group. Each group was further divided based on the application protocol. Half of the samples were stored in distilled water for 24h at 37°C for immediate SBS testing whereas the other half was subjected to thermocycling for 20,000 cycles. SBS was measured one-day post polymerization and after thermocycling using universal testing machine. SBS values and failure modes were recorded and statistically analyzed. Results: the experimental group presented significantly lower resin-dentin SBS than the control group. Thermocycling significantly lowered SBS values for both groups. When using SE mode, the experimental group reported lower resin-dentin SBS than the control group before and after thermocyclying. When using ER mode before thermocycling, no significant difference was found between the two groups, while after thermocycling, the experimental group reported significantly higher resin-dentin SBS than the control group. For both adhesive groups, mixed failure dominated with ER mode while adhesive failure dominated with SE mode. Conclusions:Addition of HA may provide resistance to degradation and offer a potential to improve resin-dentin bond stability against thermal changes when ER protocol is applied.

Effectiveness and Safety of Combined Application of Three Modes of 2940-nm Erbium:YAG and 1064-nm Neodymium:YAG Lasers in Treatment of Meibomian Gland Dysfunction.

PurposeTo study the effectiveness and safety of upper and lower eyelid treatment with combined application of three modes of 2940-nm erbium-doped yttrium aluminium garnet (Er:YAG) and 1064-nm neodymium-doped yttrium aluminium garnet (Nd:YAG) lasers in patients with baggy eyelids (formed by intraorbital fat herniation) who exhibited meibomian gland dysfunction (MGD).Patients and MethodsIn this prospective cohort study, patients with baggy eyelid who exhibited MGD received combined laser treatment at baseline, as well as at the 4-, 8-, and 12-week follow-ups. The primary endpoint was meibum quality score at 16- and 24-week follow-ups; secondary endpoints were ocular surface index scores, tear film lipid layer thicknesses, tear break up times (TBUTs), Oxford scheme grades, and meibography grades at 16- and 24-week follow-ups. Adverse events, uncorrected visual acuities, best-corrected visual acuities, and intraocular pressures were also recorded.ResultsSixteen patients (four men and 12 women; mean age, 56.38 ± 8.64 years) were included. Meibum quality scores at the 16-week follow-up were significantly lower than scores at baseline (p=0.043) and at the 24-week follow-up (p=0.015). TBUT was significantly exacerbated at the 24-week follow-up, compared with baseline (p=0.001) and the 16-week follow-up (p=0.006). There were no significant changes in other parameters. All adverse events were mild and resolved without additional treatment.ConclusionCombined application of three modes of 2940-nm Er:YAG and 1064-nm Nd:YAG lasers on upper and lower eyelids significantly improved meibum quality in patients with MGD; it ameliorated symptoms and signs of dry eye disease at 4 weeks after completion of laser treatment.

Effect of Er:YAG laser pulse duration on repair bond strength of resin-based and hybrid CAD/CAM restorative materials

Besides the output power and pulse frequency, the pulse duration of Er:YAG laser is an important parameter for conditioning the restorative material surface. This study aimed to investigate the effect of six different pulse modes of Er:YAG laser on the repair bond strength of a hybrid ceramic and two resin-based CAD/CAM restorative materials. Twenty-eight specimens (5 × 5 × 4 mm) were prepared for each CAD/CAM block (Lava Ultimate-(LU), Vita Enamic-(VE), and GC Cerasmart-(GCC)) and randomly divided into seven groups. The specimens except the control group were irradiated using Er:YAG laser at 3 W and 20 Hz using quantum square pulse (QSP), super short pulse (SSP), short pulse (SP), medium short pulse (MSP), long pulse (LP), and a very long pulse (VLP). A micro-hybrid resin composite (Filtek Z250, 3 M ESPE, USA) was placed up to 4 mm on each CAD/CAM specimen in two increments. Bar specimens (1 × 1 × 8 mm) were obtained using a cutting device and thermocycled 10,000 times at 5–55 °C. Microtensile bond strength (µTBS) test was performed at a 1 mm/min crosshead speed. Data were statistically analyzed using two-way ANOVA and Tukey’s HSD tests (p < 0.05). µTBS was significantly affected by both pulse duration and material type (p < 0.001). Pulse duration and material type showed a statistically significant interaction (p < 0.001). Except for QSP, shorter pulse modes resulted in a higher repair bond strength. VLP mode is not recommended to be used in repair procedures with the materials tested.

Dentin Permeability and Nanoleakage of Universal Adhesives in Etch-and-rinse vs Self-etch Modes.

This study evaluates the reduction in dentin permeability (P) and the expression of nanoleakage in resin-dentin interfaces made with universal adhesives, comparing the self-etch mode of application with the etch-and-rinse mode of application. To measure dentin P at the baseline and after adhesive polymerization, 80 extracted noncarious human third molars (N=80) were sectioned to obtain 0.7-mm-thick midcoronal dentin disks. The specimens were randomly assigned to 8 groups according to the different adhesive systems and application modes used: Scotchbond Universal (SBU; etch-and-rinse [ER] mode vs self-etch [SE] mode), OptiBond XTR (OPT; etch-and-rinse mode vs self-etch mode), Clearfil Universal Bond Quick (CL; etch-and-rinse mode vs self-etch mode), and Adhese Universal (ADH; etch-and-rinse mode vs self-etch mode). A two-way analysis of variance with interaction was used to evaluate the P reduction differences among the groups (α=0.05). Sixteen additional 0.7-mm-thick dentin disks were similarly prepared and treated, immersed in 50 wt% ammoniacal silver nitrate, and then processed according to conventional methods for analysis under transmission electron microscopy. The differences in P reduction among the adhesives were significant (p=0.029). For OPT and ADH (p=0.0304 and p=0.0120, respectively), the P reduction was higher in the ER mode than in the SE mode. For CL and SBU, no differences in P reduction was observed between the two application modes (p>0.05). All the groups showed some pattern of nanoleakage. No adhesive system completely reduced dentin P. Dentin sealing was higher for OPT and ADH in the ER mode, while for SBU and CL, there was no difference between the two modes. All the adhesive systems showed nanoleakage.

Influence of preprocedural antiseptic mouthrinses against COVID-19 on enamel/dentin bond strength of a universal adhesive

The aim of the study was to determine the effect of preprocedural mouthrinses used against COVID-19 on enamel/dentin shear bond strength (SBS) of a universal adhesive with different application strategies. Three hundred sound human mandibular anterior teeth were used for the study. The teeth were distributed according to the tooth substrates; enamel and dentin. After obtaining flat enamel/dentin surfaces, each substrate group was divided into a control and four experimental groups (n = 30): Group I (Control) – distilled water; Group II – 1.5% hydrogen peroxide (H2O2) (30 s); Group III – 1.5% H2O2 (60 s); Group IV – 0.2% povidone-iodine (PVP-I) (30 s); Group V – 0.2% PVP-I (60 s). Each group was then assigned into two subgroups according the application strategy of the universal adhesive, Prime & Bond Universal (n = 15); a-etch and rinse (ER) and b-self-etch (SE). The resin composite bonded assemblies were subjected to SBS testing after 24 h. The failure modes and SEM investigations were evaluated. Statistical analysis involved four-way ANOVA with pair-wise comparisons using Bonferroni correction test (p < 0.05). On enamel, the highest SBS in ER application strategy were determined for the control group, followed by PVP-I and H2O2 group, respectively (p < 0.05). For self-etch strategy, no significant difference was detected among the groups (p > 0.05). The ER application mode showed higher SBS on enamel (p < 0.05) except for group H2O2 for 30 s. There was no difference between the dentin SBS of control and mouthrinse groups regardless of application mode (p > 0.05). In comparison between the rinsing times, 60 s rinsing significantly improved the enamel SBS when ER mode was used(p < 0.05). Neither rinsing period, nor adhesive strategy affected the dentin SBS (p > 0.05). The preprocedural usage of antiseptic mouthrinses and their rinsing times affect the bonding performance of the universal adhesive only on enamel surfaces in ER mode.

Effect of an ethanol cross-linker on universal adhesive

ObjectiveTo evaluate the effects of N,N'-dicyclohexylcarbodiimide (DCC), an ethanol-based dentin cross-linker, on the immediate and long-term microtensile bond strength (μTBS) and nanoleakage expression of a universal adhesive employed in self-etch mode (SE) or etch-and-rinse mode (ER). The effect of DCC on the dentinal MMP activity was also investigated by means of in-situ zymography. MethodsEighty freshly extracted human molars were sectioned to expose mid-coronal dentin surfaces. The teeth were assigned to one of the following groups, according to the dentin surface priming/adhesive approach: (G1): DCC pre-treatment and Scotchbond Universal (SBU) in ER mode; (G2): SBU in ER mode; (G3): DCC pretreatment and SBU in SE mode; (G4): SBU in SE mode. μTBS test was performed immediately (T0) or after 1-year aging (T12) in artificial saliva. Ten additional teeth per group were prepared for nanoleakage evaluation (N = 5) and for in-situ zymography (N = 5). ResultsThree-factor analysis of variance revealed significant difference for the variables DCC pretreatment, application mode and aging (p < 0.05) for both microtensile bond strength testing and in-situ zymography. Nanoleakage analysis revealed reduced marginal infiltration of DCC experimental groups both at T0 and T12. SignificanceThe use of an ethanol-based primer containing DCC appears to be promising in preserving the stability of the adhesive interface of a universal adhesive, especially in the SE mode.

Bond durability of contemporary universal adhesives: effect of dentin treatments and aging

The aim of this in vitro investigation was to evaluate the effects of different dentin treatments on µTBS values of three different universal adhesives. Sixty extracted bovine incisors were used. The teeth were horizontally sectioned from the enamel-cement junction and embedded in an acrylic resin. Enamel was removed with 180-grit SiC paper to expose dentin. The exposed dentin surfaces were further polished with 600-grit SiC paper to provide a standardized smear layer. Teeth were randomly divided into three groups, according to the universal adhesives: All-Bond Universal, Single Bond Universal, and G-Bond Plus. Each group was then assigned into four subgroups, according to the dentin treatments: etch-and-rinse mode (ER), ER + 2% chlorhexidine (CHX), ER + %2.5 genipin (GE), and self-etch mode (SE). Samples were longitudinally sectioned across the bonded-interfaces to obtain resin-dentin beams. Beams were prepared from the same teeth were randomly and equally divided into two groups: immediate µTBS testing and µTBS testing after 6-month. The failure loads were recorded in MPa, and failure modes were evaluated at 30× magnification. The data were analyzed using a two-way ANOVA, to determine the effects of dentin treatment and storage time, and the interaction of these two factors on the µTBS of universal adhesives. Dentin treatments were showed significant differences (p < 0.05). ER mode exhibited higher µTBS than SE mode. However, universal adhesives were more durable in the SE mode than ER mode. Also, chlorhexidine treatment significantly improved adhesive performance of all universal adhesives, while no significant improvement was detected with genipin treatment.

Repair bond strength of composite to Er,Cr:YSGG laser irradiated zirconia and porcelain surfaces

BackgroundFracture or chipping are major concerning failures of an all-ceramic restoration. Repairing of the failure restoration using intra-oral technique is time saving and cost effective treatment modality. The present study was proposed to evaluate effect of Er,Cr:YSGG laser irradiation on shear bond strength between zirconia/porcelain and composite resin. MethodsThirty zirconia and thirty zirconia based porcelain disc shape specimens were prepared. Three different surface treatment procedure were applied the specimens. For control groups (Group ZC and PC), instruction manual of an intra-oral porcelain repair system was followed. Different pulse rates of Er,Cr:YSGG laser irradiation (short and long pulses) were applied to zirconia and porcelain surfaces for other groups (Group ZS, ZL, PS, and PL). Porcelain repair kit was used to repair specimens using standard cylindrical teflon mold (2 × 2 mm). Repair bond strength of the repaired specimens was tested using a universal testing machine. ResultsHighest mean bond strength value was observed at Group PC that was significantly higher than laser applied porcelain groups. Long pulse laser irradiation illustrated that increased mean bond strength compared to short pulse application on to the porcelain surface. Laser applied zirconia groups showed better mean bond strength than Group ZC, but differences between the groups were not statistically significant. ConclusionDifferent modes of Er,Cr:YSGG laser irradiation enhanced repair bond strength of the composite resin to zirconia, but these were not significant. Following the instruction manual for surface treatment on the porcelain surface was better method than Er,Cr:YSGG laser surface conditioning.

Non-invasive identification of paint binders in illuminated manuscripts by ER-FTIR spectroscopy: a systematic study of the influence of different pigments on the binders\u2019 characteristic spectral features

This paper presents the results of a study of pigment-binder systems painted on parchment, both in the form of reference samples prepared in the laboratory, and of medieval and Renaissance illuminated manuscripts, by means of contactless Fourier-transform mid-infrared spectroscopy (FTIR). The research is aimed at validating external reflection FTIR (ER-FTIR) as a non-invasive method for the identification of paint binders in works of art on parchment. Based on a systematic FTIR investigation undertaken both in attenuated total reflection (ATR) and ER mode, we discuss the possibility to effectively discriminate between different binders, and the way in which the presence of a number of pigments can modify the spectral features of the pigment-binder system. The study reveals that gum Arabic can usually be discriminated from egg-based binders such as egg yolk and egg white, both in paintouts and in real artworks. Amongst all the pigments investigated, carbonates such as azurite and lead white are those that most significantly hinder the correct identification of the paint medium.

Does the Conditioning Mode and Duration of Universal Adhesives Affect the Bonding Effectiveness to Fluorotic Enamel?

To compare the adhesive-enamel microshear bond strength (µSBS), in situ degree of conversion (DC), and the enamel-etching pattern of universal adhesives when applied for a prolonged period in the self-etch vs the etch-and-rinse mode in fluorotic enamel. Ninety-six human molars (48 with a Thylstrup and Fejerskov index [TFI] score of 0 and 48 with TFI score of 4) were sectioned into four parts and divided into 24 experimental groups based on enamel surface (sound enamel or fluorotic enamel), adhesive (Clearfil Universal Bond, Futurabond U, iBond Universal, or Scotchbond Universal), and enamel treatment/application time (etch-and-rinse mode [ER] or self-etch mode with application times of 20 s [20SE] and 40 s [40SE]). The specimens were stored for 24 h and tested in shear at 1.0 mm/min (μSBS). Adhesive-enamel interfaces were evaluated for DC using micro-Raman spectroscopy. The enamel-etching pattern was evaluated using SEM. For each adhesive, data from µSBS and DC were analyzed separately using two-way ANOVA and Tukey's post-hoc test at α = 0.05. On sound enamel, 40SE usually resulted in statistically similar mean µSBS (p > 0.52) and statistically significantly improved mean DC values (p < 0.001) compared with the ER mode. Moreover, significantly improved mean µSBS and DC values were obtained compared with 20SE (p < 0.01). On fluorotic enamel, there was no statistically significant difference in µSBS between the experimental groups (p > 0.76). However, for each applied adhesive, 40SE resulted in improved mean DC values compared with 20SE or ER (p < 0.001). The deepest enamel-etching pattern was obtained in ER mode, followed by 40SE in sound and fluorotic enamel. Compared with ER mode, the prolonged application time of universal adhesives in SE mode in fluorotic enamel increased the DC, enhanced enamel-etching pattern and promoted similar results in terms of adhesive-enamel bond strength.

Effect of adhesive mode and chlorhexidine on microtensile strength of universal bonding agent to sound and caries-affected dentins.

Objective:The main objective of this study is to assess the effect of the adhesive mode and chlorhexidine (CHX) on the microtensile strength of a universal bonding agent to sound and caries-affected dentins.Materials and Methods:Six intact third molars and six decayed third molars were sectioned to obtain two middle dentin specimens per tooth. Prime and Bond Elect Universal (Dentsply) was applied to specimens in two different modes: Etch-and-rinse (ER, phosphoric acid for 15s) and self-etch (SE, no phosphoric acid). 2% CHX (Cavity Cleanser, Bisco) was applied to both dentins for 30 s. Specimens were randomly assigned into eight groups (n = 3) according to the treatments applied to sound and caries-affected dentins: SE; ER; SE + CHX; and ER + CHX. All specimens were restored with TPH Spectra High Viscosity (Dentsply) composite resin and sectioned to obtain specimens of 0.8 ± 0.1 mm2. The microtensile bond strength test was conducted at 1 mm/min. The data were statistically analyzed by ANOVA and multiple comparisons’ test (α = 0.05).Results:There was no significant difference between sound dentin and caries-affected dentin (P = 0.132). The highest bond strength was obtained with the application of the ER (31.81MPa). SE + CHX promoted the lowest bond strength with no statistical difference to ER + CHX (P > 0.05).Conclusions:ER mode for the universal bonding agent yielded the highest bond strength to sound and caries-affected dentins. CHX reduced the bond strength to both dentins regardless the application of phosphoric acid.Clinical Significance:The universal bonding agent increased the bond strength to sound and caries-affected dentins when applied by the ER mode.

Bond Strength and Cytotoxicity of a Universal Adhesive According to the Hybridization Strategies to Dentin.

This study evaluated application protocol (etch-and-rinse/ER and self-etching/SE) and dentin wettability (wet and dry) on microtensile bond strength (μTBS) and transdentinal cytotoxicity of ScotchbondTM Universal (SU) adhesive system. The μTBS values and fracture mode were registered 24 h after adhesive system application and resin composite block build-up (n=5). For analysis of transdentinal cytotoxicity, odontoblast-like MDPC-23 cells were seeded on pulpal surface of dentin discs (0.4 mm thick) adapted to artificial pulp chambers (n=8). The adhesive system was applied to occlusal surface, followed by 24-h incubation time. Cell viability (Alamar Blue) and morphology (SEM) were assessed. Adper Single Bond 2 and Clearfil SE Bond were used as positive controls of the ER and SE application protocols, respectively. No treatment was performed on negative control (NC) group. Data were analyzed by ANOVA and Tukey's tests (α=5%). Higher μTBS values were found for ER mode in comparison with SE protocol (p<0.05). Dentin wettability had no effect on bond strength of SU in both the ER and SE techniques (p>0.05). Most fractures involved hybrid layer and/or adhesive layer. Neither variable prevented the intense toxic effects of adhesive systems on MDPC-23 cultured cells, since intense reduction in cell viability (±88%) and severe alterations in cell morphology were observed for all groups compared to NC, with no differences among them (p>0.05). Therefore, it was concluded that application of SU following the ER protocol had better adhesive performance. However, this adhesive system featured intense transdentinal cytotoxicity to pulp cells, regardless of application protocol and dentin wettability.

Efficiency of Er:YAG laser in debonding of porcelain laminate veneers by contact and non-contact laser application modes (in vitro study).

To determine the efficiency of debonding porcelain laminate veneers (PLV) by using several laser parameters and two different application modes of Er:YAG laser [contact (CM) and non-contact (NCM)], by verification of the consumed PLV debonding time and the changes in dental pulp temperature. Forty extracted non-carious human maxillary premolars were prepared for receiving PLV. Sixteen of them were divided into two groups, each of them comprised eight samples based on the application mode; group A with NCM, and group B with CM. Veneers of both groups were debonded by the same laser parameters (360 mJ, 15 Hz) during loading of a 15 N force on specially fabricated veneer cervical margins. The primary results showed that the NCM was more efficient, thus, additional groups (C, D, and E) of the same mode and number of samples were tested with different laser parameters of energy and frequency; group C (400 mJ, 10 Hz), group D (270 mJ, 15 Hz), group E (300 mJ, 10 Hz). The failure mode was determined and classified for the debonded samples of all groups. All veneers were debonded and samples of the NCM group had considerably lower debonding time (12.6 seconds) than the CM samples (96.3 seconds), however, higher changes of temperature in NCM (4.2°C) than in CM were observed (2.9°C). The failure mode of samples was either type 1 or 3. Er:YAG laser is an effective tool in debonding PLVs. The NCM application mode was more efficient in reducing debonding time than CM application mode but with a higher change in pulp temperature. Investigating the efficacy of Er:YAG laser as a non-invasive particle technique for debonding of failed or malpositioned of porcelain laminated veneers.

Efficacy of removal of cariogenic bacteria and carious dentin by ablation using different modes of Er:YAG lasers.

The primary objective of this in vitro study was to evaluate the efficiency of removal of cariogenic bacteria and carious dentin by ablation using two lasers: fluorescence-feedback controlled (FFC) Er:YAG laser and different pulses of Er:YAG laser based on variable square pulse technology (VSPt). The secondary objective was to measure the temperature during laser ablation of carious tissue. Seventy-two extracted human molars were used in this study. Sixty teeth with carious dentin were randomly divided into four experimental groups according to the treatment for caries removal: group 1: 400 µs (FFC group); group 2: super short pulse (SSP group, 50 µs pulse); group 3: medium short pulse (MSP group, 100 µs pulse); group 4: short pulse (SP group, 300 µs pulse) and one positive control group with no treatment. Twelve teeth without carious lesion were used as a negative control group. After caries removal, swabs were taken with cotton pellets and real-time PCR analysis was performed. During caries ablation, a thermal infrared camera was used to measure the temperature changes. In all experimental groups, specimens were free of bacterial contamination after the treatment. In the SSP, MSP and SP groups, temperatures measured during caries ablation were significantly higher compared to temperatures in the FFC group (P<0.001). In this in vitro study, laser treatment for removal of carious dentin and cariogenic bacteria was an efficient treatment modality without causing excessive temperatures that might adversely affect pulp vitality.

Effect of different modes of erbium:yttrium aluminum garnet laser on shear bond strength to dentin.

The aim of this study was to evaluate the effect of different surface treatments on the shear bond strength (SBS) of resin composites to dentin using total etch dentin bonding adhesives. Sixty extracted human molars were flattened to obtain dentin surfaces. The samples were divided into three groups (n = 20): Group I: 37% phosphoric acid + optibond FL + resin composite; Group II: Erbium:yttrium aluminum garnet (Er:YAG) laser (medium short pulse [MSP] mode, 120 mJ/10 Hz) + optibond FL + resin composite; Group III: Er:YAG laser (quantum square pulse [QSP] mode, 120 mJ/10 Hz) + optibond FL + resin composite. After the specimens were prepared, the SBS test was performed at a crosshead speed of 0.5 mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. Statistical analyses were performed with one-way ANOVA and Tukey's honestly significant difference tests. One sample of treated dentin surface from each group was sputter-coated with gold, and scanning electron microscope (SEM) images were captured. Acid etching showed significantly higher SBS than the other groups (P < 0.05). However, the difference between Er:YAG MSP and QSP mode groups was not statistically significant (P > 0.05). SEM images of the acid-etched dentin surface showed opened dentinal tubule with a regular surface, but Er:YAG MSP mode treated surface was irregular. The surface treated with Er:YAG QSP mode represented wide dentinal tubules with a clean and flat surface. Using different modes (MSP and QSP) of Er:YAG laser for dentin surface treatment before application of total etch adhesives is still not an sufficient alternative compared to acid etching.

Evaluation of the Efficacy of Ablative vs. Fractional Er:YAG Laser Modes as a Treatment of Post-Burn Scars

Aim: To determine the effect of Er:YAG laser in the management of post-burn scars and to compare its effect to ablative and fractional lasers.Patients and methods: 50 patients with post-burn scars were recruited and randomly divided into 2 groups: Group I patients had ablative Er:YAG laser mode therapy and Group II patients had fractional Er:YAG laser rmode therapy. Vancouver scar score (VSS) was recorded for each group pre- and postoperatively, both groups showed an increase in the VSS and histopathological findings.Results: The obtained results showed morphological changes immediately after treatment, the skin surface displayed a white-gray frost, which on close inspection revealed a point pattern corresponding to individual laser columns done by fractional laser treatment.Conclusion: Ablative and fractional modes of Er:Yag laser can be used for treatment of post-burn hypertrophic scars. Ablative laser mode had better results than fractional laser mode as indicated by clinical assessment, VSS and changes of histopathological findings.

Effect of silane contamination on dentin bond strength

Statement of problemIntraoral repair of porcelain or other silica-based ceramics typically requires the use of silane in the repair protocol. Some porcelain intraoral repairs also involve bonding to exposed or involved tooth tissues including dentin. A study is needed to evaluate whether the cross-contamination of dentin with silane affects bond strength to this tissue. PurposeThe purpose of this in vitro study was to investigate the effect of silane cross-contamination on dentin bond strength. Material and methodsFlat surfaces of human dentin specimens were created, followed by wet polishing with 320-grit silicon carbide paper. The dentin specimens were divided into 4 groups: group SE (All-Bond Universal Adhesive used in self-etching mode); group SiSE (silane applied to dentin followed by All-Bond Universal Adhesive used in self-etching mode); group ER (All-Bond Universal Adhesive used in total-etch (etch-and-rinse) mode); and group ERSi (Etch and rinse and silane applied to dentin followed by All-Bond Universal Adhesive). The dentin specimens were treated with a universal adhesive (All-Bond Universal) and bonded with a composite resin, using an Ultradent jig mold. Shear bond strength (n=10) was measured after 24 hours of water storage at 37°C. After the shear bond strength test, the dentin sides of fractured specimens in each group were examined with a stereomicroscope at ×15 magnification to determine failure modes. Data were statistically analyzed by 2-way and a 1-way ANOVA followed by post hoc Tukey honest significant difference test (α=.05). Scanning electron microscopy examination was used to evaluate the dentin surface morphology before and after bonding. ResultsThe shear bond strength of composite resin to dentin was not affected adversely when the dentin was contaminated with silane prior to using All-Bond Universal in the self-etch or total- etch (phosphoric acid) mode. SE, 30.3 ±3.8 MPa; SiSE, 32.9 ±3.9 MPa; ER, 34.9 ±3.1 MPa; ERSi: 35.2 ±4.9 MPa (P>.05) ConclusionsUnder the conditions of this study, cross-contamination of dentin with silane before the use of All-Bond Universal in the self-etch or total-etch with phosphoric acid mode did not adversely affect composite resin bond strength to dentin.