Comparative Assessment of pH and Degree of Surface Roughness of Enamel When Etched with Five Commercially Available Etchants: An In Vitro Study.

AIM: To evaluate the pH and degree of surface roughness caused by five commercially and readily available etchants on tooth enamel. MATERIALS AND METHODS: Five different etchants were chosen. An electric pH meter was utilized to test the pH of the etchants employed. Fifteen maxillary bicuspids that had been extracted were cleansed and stored in thymol solution. The samples were sorted into five groups of three each. A noncontact profilometer was employed to assess the microsurface changes of the pre-etched enamel. The teeth were then etched for 30 seconds with respect to the group to which they belonged before being cleaned and dried. The surface roughness after etching was analyzed, measured and values were tabulated. Descriptive statistics and paired t-test were done. RESULTS: The pH of the etchants and surface roughness of the enamel are varied across the five groups, though they have the same composition of 37% orthophosphoric acid. Etchant from Group C was found to be most acidic while the one manufactured by Group E was least acidic. Ivoclar, DPI, and DTECH showed a statistically significant value in surface roughness parameter post-etching (p <0.05). A statistical difference that was significant was observed with the Kruskal-Wallis test for surface roughness parameter (p <0.05). CONCLUSION: All five etchants had varied pH and the amount of surface roughness was also varied though the composition was the same. Further elemental analysis of these etchants has to be done to validate the results obtained. CLINICAL SIGNIFICANCE: Etchants of the same composition should ideally produce the same effect on the tooth enamel surface, but etchants from different manufacturers produce different levels of surface roughness which could be due to differences in the composition of the prepared etchant. The study was conducted to assist in making an educated selection about the most cost-effective but efficient etchant for clinical application.

[Comparative assessment of the human blood plasma impact on the properties of various adhesive systems]. / Sravnitel'naya otsenka stepeni vliyaniya plazmy krovi cheloveka na svoistva razlichnykh adgezivnykh sistem.

OBJECTIVE: To assess the degree of influence of human blood plasma simulating dentinal fluid on the composite resin adhesion to dental hard tissues. MATERIAL AND METHODS: The strength of the adhesive bond between the composite material and dental hard tissues was studied using a shear test machine Zwick Roell Z 010 («Zwick¼, Germany) on extracted human teeth. XP Bond one-component adhesive system and XENOV self-etching adhesive system (DENTSPLY, Germany), high-definition micrometric restoration material Esthet X HD (DENTSPLY, Germany), as well as centrifuged blood plasma were used. RESULTS: Adhesion strength decreased by 26-78% when blood plasma weighing from 0.2 to 2.0 mg mixed up the self-etching system (weight 6.6 mg). A significant decrease in the adhesion force occurred when plasma with a mass of 0.7 mg or more mixed up with the monomer (a decrease in adhesion by 19.1%). A critical decrease in the adhesion force (43% or more) occurred with the mixture of blood plasma weighing 2.0 mg or more.

Assessment of microcracks and shear bond strength after debonding orthodontic ceramic brackets on enamel priorly etched by different Er,Cr:YSGG and Er:YAG laser settings without acid application: An in vitro study.

BACKGROUND DATA: Enamel microcrack formation has a high incidence after mechanical debonding of ceramic brackets. This may be due to high delivered shear bond strength values when enamel is priorly etched by phosphoric acid. It is still not well elucidated in the literature if laser etching affects enamel the same way. The aim of the research was to analyze different Er,Cr:YSGG and Er:YAG laser etching settings as an alternative to phosphoric acid, in an attempt to prevent enamel microcrack formation during laser etching and mechanical debonding, while reducing the shear bond strength to the minimal clinical acceptable value. MATERIALS AND METHODS: One hundred and thirty-three teeth were randomly divided into 7 experimental groups according to their etching modalities. Settings used for enamel etching were in Er,Cr:YSGG groups: Er,Cr:YSGG (1.5Watt, W/20Hertz, Hz); Er,Cr:YSGG (1.5W/15Hz) and Er,Cr:YSGG (2W/20Hz) and settings used for enamel etching in Er:YAG groups were: Er:YAG (60 millijoules, mJ), Er:YAG (80mJ) and Er:YAG (100mJ). Group C etched with 37% phosphoric acid served as control. Microscopic analysis was performed to assess presence of enamel microcracks. Shear bond strength was evaluated after thermocycling using Weibull survival analysis. RESULTS: All groups showed a reduction in additional microcracks after debonding when compared to control, but only group Er:YAG (60mJ) exhibited a statistically significant difference. Groups Er:YAG (80mJ), control and Er:YAG (100mJ) showed respectively the highest probability of survival at various stress levels followed by groups Er:YAG (60mJ); Er,Cr:YSGG (1.5W/15Hz); Er,Cr:YSGG (2W/20Hz) and Er,Cr:YSGG (1.5W/20Hz) that presented a relatively considerable risk of failure, even at low stress levels. CONCLUSIONS: When considering reduction of enamel microcrack formation and clinical acceptable shear bond strength, none of the groups succeeded both. Etching by Er:YAG (60mJ) and Er,Cr:YSGG (1.5W/15Hz), showed the least overall microcrack incidence between groups, but Er:YAG (60mJ) displayed significant reduction compared to phosphoric acid. However, etching by Er:YAG (80mJ) had the most predictable results in term of shear bond strength.

In vitro assessment of ribose modified two-step etch-and-rinse dentine adhesive.

OBJECTIVE: Collagen fibrils aid in anchoring resin composite restorations to the dentine substrate. The aim of the study was to investigate effect of non-enzymatic glycation on bond strength and durability of demineralized dentine specimens in a modified two-step etch-and-rinse dentine adhesive. METHODS: Dentine surfaces were etched with 37% phosphoric acid, bonded with respective in vitro ethanol and acetone adhesives modified with (m/m, 0, 1%, 2% and 3% ribose), restored with restorative composite-resin, and sectioned into resin-dentine slabs and beams to be stored for 24h or 12 months in artificial saliva. Bond-strength testing was performed with bond failure analysis. Pentosidine assay was performed on demineralized ribose modified dentine specimens with HPLC sensitive fluorescent detection. The structural variations of ribose-modified dentine were analysed using TEM and human dental pulpal cells were used for cell viability. Three-point bending test of ribose-modified dentine beams were performed and depth of penetration of adhesives evaluated with micro-Raman spectroscopy. The MMP-2 and cathepsin K activities in ribose-treated dentine powder were also quantified using ELISA. Bond strength data was expressed using two-way ANOVA followed by Tukey's test. Paired T tests were used to analyse the specimens for pentosidine crosslinks. The modulus of elasticity and dentinal MMP-2 and cathepsin K concentrations was separately analyzed using one-way ANOVA. RESULTS: The incorporation of RB in the experimental two-step etch-and-rinse adhesive at 1% improved the adhesive bond strength without adversely affecting the degree of polymerisation. The newly developed adhesive increases the resistance of dentine collagen to degradation by inhibiting endogenous matrix metalloproteinases and cysteine cathepsins. The application of RB to acid-etched dentine helps maintain the mechanical properties. SIGNIFICANCE: The incorporation of 1%RB can be considered as a potential candidate stabilizing resin dentine bond.

Assessment of enamel cracks at adhesive cavosurface margin using three-dimensional swept-source optical coherence tomography.

OBJECTIVES: Swept-source optical coherence tomography (SS-OCT) can construct cross-sectional images of internal biological structures. The aim of this study was to evaluate enamel cracks at the cavosurface margin of composite restorations using SS-OCT. METHODS: Bowl-shaped cavities were prepared at two locations (mid-coronal and cervical regions) on the enamel surface of 60 bovine teeth. Half of the cavities (30) were treated with phosphoric acid gel. A two-step self-etch adhesive (Clearfil SE Bond) was applied to all cavities and a flowable composite was placed in bulk. After 7days in water at 37°C, three-dimensional (3D) images of the specimens were obtained using SS-OCT, and cross-sectional views of the cavosurface margin were examined. Presence and extent of enamel cracks along the cavosurface margin circumference were evaluated using a 5-point scale. The results were statistically compared with Wilcoxon rank sum test with Bonferroni correction. RESULTS: 3D SS-OCT could detect enamel cracks at the cavosurface margin of composite restorations. Cervical regions caused more enamel cracking than mid-coronal regions. Phosphoric acid etching increased the incidence of enamel cracks compared with the preparations without etching. CONCLUSION: SS-OCT can be used to detect enamel cracks at the margins of composite restorations noninvasively. Presence and extent of enamel cracks depended on the enamel region and bonding protocol. CLINICAL SIGNIFICANCE: SS-OCT can be used to detect enamel cracks at the margins of composite restorations noninvasively. Selective phosphoric acid etching of the enamel significantly increased the incidence of marginal cracks, especially in cervical preparation.

An experimental in vivo procedure for the standardised assessment of sealants retention over time.

AIM: The elaboration of an experimental system to obtain reproducible and comparable photographs of the occlusal surface to monitor sealants retention. MATERIALS AND METHODS: An intraoral camera connected to a computer was used to obtain photos of the occlusal surfaces. A specific software was utilized to perform measurements on archived pictures. An experimental two-part system, consisting of a dental arch support and a camera support, connected to each other through holes and pins, was made to obtain a standardised and reproducible placement of the camera in the mouth. In the first part, to test the degree of reliability of the procedure and the percentage of image distortion, 120 first molars were sealed and for each molar ten photographs were taken, using the intraoral camera connected with the dental arch support, the camera support and the dedicated software. In the second part, 165 first molars were sealed and photographed, as above described, immediately after sealing (T0), 6 months (T1) and 1 year later (T2). With the software, the sealed areas were measured. The comparison of the selected sealed areas between T0 and T1, T0 and T2, T1 and T2 determined the percentage of sealant loss. RESULTS: In the first part, the experimental procedure showed a reliability of 96.85%. In the second part, the difference in the rate of lost sealant between T0-T1 and T1-T2 was statistically significant (p <0.001). STATISTICS: ANOVA analysis was made. CONCLUSIONS: Photographs, obtained through the experimental two-part system, allowing a reproducible positioning of the intraoral camera in oral cavity, could represent a standardised and useful method to monitor sealants retention over time.

Assessment of Enamel Bond Strength of Hypoplastic Primary Teeth.

PURPOSE: The purpose of this study was to compare the enamel bond strength of hypoplastic and healthy primary teeth. METHODS: Twenty-five hypoplastic teeth (experimental group) and 25 healthy primary teeth (control group) were selected and conditioned with 35 percent orthophosphoric acid before a two-layer adhesive system (Single Bond) was applied. Composite resin (Filtek Z350) was inserted in a single application, two-mm high and one-mm in diameter, and then light-cured for 20 seconds. After being stored in distilled water for 24 hours, the specimens were submitted to a shear bond strength test. Fractures were analyzed under a stereomicroscope. RESULTS: No significant differences in bond strength were observed between the experimental group (70.27±20.40 MPa) and control group (67.84±23.37 MPa; P>0.05). However, adhesive fractures were more frequently observed in healthy teeth (72 percent) while hypoplastic teeth presented mixed fractures (60 percent) and enamel cohesive fractures (36 percent). CONCLUSIONS: The shear bond strength of the enamel of hypoplastic primary teeth was similar to that of healthy teeth. However, distinct characteristics were observed in the dental samples following fracture.

In vitro assessment of retention and microleakage in pit and fissure sealants following enamel pre-etching with sodium hypochlorite deproteinisation.

AIM: The purpose of this study was to assess and compare the rate of sealant retention and microleakage after placement on etched enamel with and without prior deproteinisation. STUDY DESIGN: 75 freshly extracted third molars were randomly assigned to either of two pit and fissure treatment methods. Samples from both groups were etched with 37% phosphoric acid gel for 15 seconds, followed by placement of a sealant, and then subjected to thermocycling for evaluation of sealant retention. After that, specimens were immersed in rhodamine B, sectioned longitudinally, and examined under a confocal laser scanning microscope for assessment of microleakage. Collected data were statistically analysed using chi-square and Fisher exact tests with an α level of 0.05. RESULTS: The rate of sealant retention was similar between the two study groups (P = 0.073), but the rate of sealant microleakage was significantly lower in the enamel deproteinisation group (P < 0.001) than in the control group. CONCLUSION: Based on these findings, we recommend the deproteinisation method prior to enamel acid etching to obtain better clinical results with sealants.

Fibre-reinforced composite (FRC) bridge--a minimally destructive approach.

Replacing missing teeth is an integral part of the clinical services of the dental practitioner. The fibre-reinforced composite (FRC) bridge is a relatively new method for replacing missing teeth. This article will explain and discuss this alternative treatment option. Practical instructions on how to construct a FRC bridge will be given, by means of a clinical case. Different technique options will be illustrated to provide the reader with a good understanding of the most practical way to use the FRC strips. The fibre-reinforced composite provides a non-destructive, aesthetically pleasing and cost-effective way to restore missing teeth. Clinical Relevance: Minimally invasive options should always be considered and destruction of healthy enamel and dentine during the preparation phase of a replacement treatment should be avoided as much as possible.

Effects of sandblasting before orthophosphoric acid etching on lingual enamel: in-vitro roughness assessment.

INTRODUCTION: In this study, we evaluated changes in lingual enamel roughness due to sandblasting with 27-, 50-, and 90-µm aluminum oxide particles followed by 37% orthophosphoric acid etching. METHODS: Twenty-four maxillary premolars were included in the study. The lingual enamel roughness of 20 teeth was evaluated using a laser confocal microscope before and after enamel conditioning. Group 1 (control) was etched with 37% orthophosphoric acid; groups 2, 3, and 4 were sandblasted with 27-, 50-, and 90-µm aluminum oxide particles, respectively, before acid etching. The lingual surfaces of the other 4 teeth were evaluated using scanning electron microscopy after they had received one of the conditioning methods under study. Paired t tests were used to compare the roughness parameters obtained before and after conditioning in each group, and 1-way analysis of variance was used to compare the surface roughness between groups. The significance level was set at 5% for all statistical analyses. RESULTS: The 4 conditioning methods significantly increased the roughness of the lingual enamel. However, the roughness increases in the groups that were sandblasted with 27-, 50-, and 90-µm aluminum oxide particles before orthophosphoric acid etching were statistically greater than was the increase in the group conditioned only with orthophosphoric acid. Scanning electron microscopy showed different conditioning patterns among specimens that were conditioned only with orthophosphoric acid and those sandblasted with aluminum oxide before acid etching. CONCLUSIONS: Lingual enamel conditioning with aluminum oxide sandblasting before acid etching results in greater roughness and produces a conditioning pattern different from that of acid etching alone.

Efficiency and effectiveness evaluation of three glass fiber post removal techniques using dental structure wear assessment method.

AIM: This study evaluated the efficiency and effectiveness of three glass fiber post removal techniques. MATERIALS AND METHODS: Forty-five extracted maxillary teeth were endodontically treated and cross-sectioned in thirds. Presence of cementing agent and dental structure wear were assessed by analyzing images taken before luting of glass fiber post and after removal procedure. Teeth were divided into 3 groups: Group 1 - diamond bur + Largo reamer; Group 2 - ultrasonic insert; Group 3 - carbide bur + ultrasonic insert. Time spent on removal procedures, dental structure wear and amount of remaining cement agent were recorded and results submitted to ANOVA, Kruskal Wallis and Tukey-Kramer tests. RESULTS: Group 1 - 16'46", 33.33% and 6.99%; Group 2 - 12'31", 40% and 7.86%; and Group 3 - 10'24", 80% and 8.14%. Group 3 presented the most effective removal of glass fiber posts. CONCLUSION: There was no significant difference in efficiency among the evaluated techniques.

Survival analysis of brackets and tubes: A twelve-month assessment.

OBJECTIVE: To compare the clinical performance of brackets bonded to anterior and posterior teeth, including second molars. MATERIALS AND METHODS: One operator, using the straight-wire technique, bonded metallic brackets to the teeth of 127 consecutive patients. All patients were observed for 12 months during their regular orthodontic appointments. Bracket failures were recorded and summarized for statistical analysis. The Cox proportional hazards regression analysis was performed to evaluate bracket failure rates. RESULTS: Statistically significant differences in survival rates were observed between molar tubes and anterior brackets (P < .05). Twelve-month failure rates of incisor, canine, premolar, and molar brackets were 3.6, 1.6, 4.8, and 11.6%, respectively. The first and second molar did not show significant difference in bond failure. Young patients (age <18 years) showed a higher failure rate than old patients (≥18 years). CONCLUSIONS: Brackets directly bonded to the buccal surfaces of molars failed significantly more often than those directly bonded to anterior teeth or premolars, but showed acceptable failure rate especially in adult patients. Bonding on second molars seems to be as reliable as bonding on the first molars.

Impact of intracoronal dentin treatment prior to bleaching on bond strength of restorative materials.

Surface treatment of dentin before the bleaching procedure may affect its permeability and influence the bond strength of restorative materials. This study evaluated the influence of surface treatment before the bleaching on shear bond strength (SBT) of restorative materials to intracoronal dentin. Dentin slabs were subjected to surface treatment: no bleaching (control - CON), no surface treatment + bleaching (HP), 37% phosphoric acid + bleaching (PA) and Er:YAG laser + bleaching (L). After the bleaching procedure, specimens (n=10) were restored with: microhybrid composite resin (MH), flowable composite resin (F), and resin-modified glass-ionomer cement (RMGIC). The shear test was carried out. ANOVA and Tukey's test (α=0.05) showed significant difference for surface treatment and restorative materials (p<0.05). CON presented higher STB and was statistically different from HP (p<0.05). PA and L showed intermediate values and were statistically similar to CON and HP (p>0.05). STB for MH and F were higher than RMGIC (p<0.05), and did not differ from each other (p>0.05). The surface treatments with phosphoric acid and Er:YAG laser before the bleaching procedure provided shear bond strength at the same level of unbleached dentin and the composite resins presented superior bond strength to the intracoronal dentin.

Microbial microleakage assessment of a new hydrophilic fissure sealant: a laboratory study.

PURPOSE: The purpose of this study was to compare microbial leakage of a new hydrophilic sealant with that of a conventional hydrophobic resin-based sealant. METHODS: One hundred extracted, caries-free, human maxillary premolars were randomly divided into five groups. Those in Groups 1, 2, and 3 had dry, wet, and artificial saliva-contaminated occlusal surfaces, respectively, and were sealed with a hydrophilic sealant, while those in Groups 4 and 5 had dry and wet occlusal surfaces, respectively, and were sealed with a hydrophobic sealant. A newly designed microbial penetration method utilizing Streptococcus mutans as an indicator was tested for leakage assessment. Data were analyzed using SPSS 15.0 software, and the significance level was set at α=0.05. RESULTS: The log rank test indicated a statistically significant difference in leakage rates among the five groups. Mantel-Cox log-rank test findings showed that Group 3 had the highest leakage rate, with Groups 2 and 4 having the lowest. There was no statistically significant difference in leakage rate between Groups 2 and 4. CONCLUSIONS: With respect to the limitations of an in vitro study, our findings suggest that hydrophilic sealants are an acceptable alternative to hydrophobic sealants.

Bonded functional esthetic prototype: an alternative pre-treatment mock-up technique and cost-effective medium-term esthetic solution.

As the economy has receded in recent years, many patients have been inclined to reject dental treatment beyond what they feel is the minimal amount necessary. Increasingly, there has been reluctance to take on the expense of full-mouth restorations and time-consuming procedures. Consequently, clinicians can benefit from innovative, conservative, interim solutions that enable them to provide segment treatment with long-term stability and esthetics, with lower initial cost. The bonded functional esthetic prototype (BFEP) allows fabrication of up to 14 teeth from composite in 1 hour, providing either a pre-treatment restoration or a long-term provisional solution until further treatment can be completed. As demonstrated herein, the BFEP enables superb function, stability, and esthetics in the interim while dispersing the cost of definitive treatment over time.

Bonded molar tubes: a survey of their use by specialist orthodontists.

OBJECTIVE: To investigate the use of bonded molar tubes (BMTs) by specialist orthodontists. DESIGN: Prospective postal questionnaire. SETTING: Ireland. PARTICIPANTS: Registered members of the Orthodontic Society of Ireland. METHODS: A questionnaire was posted to registered members of the Orthodontic Society of Ireland. It investigated demographics, pattern of use, reasons for use and techniques for placement of BMTs. RESULTS: A 74% response rate was obtained. In more than 80% of cases, BMTs were used on first and second permanent molars by 52% and 33% of orthodontists respectively. BMT usage was adopted by 97% of respondents in the previous decade. Direct bonding was used by all for BMT placement. Etch times for molars, compared to other teeth, increased from 15 to 30 seconds by 51% of orthodontists. Of the respondents, 97% used light-cured adhesives and 17% used self-etching primers. Molar tube holders were preferred by 54% for placement. Only with a history of epilepsy, were bands preferred to BMTs. BMTs were regarded as more cost-effective than molar bands by 66% of responding clinicians. CONCLUSIONS: Specialist orthodontists preferred BMTs to bands on first permenent molars. Direct bonding was favoured using a 30-second etch, a light-cured primer and adhesive with specialized molar tube holders. BMTs were perceived to be more cost-effective than molar bands.

Assessment of laminate technique using glass ionomer and resin composite for restoration of root filled teeth.

OBJECTIVE: To evaluate the open laminate technique using glass ionomer cements (GIC) in association with a low shrink composite for restoring root filled premolars. METHODS: Extensive MOD cavities plus endodontic access and root filling were performed in intact extracted maxillary premolars. Three restoration types were evaluated: (1) resin composite alone; (2) resin-modified GIC (RM-GIC) open laminate plus resin composite; (3) conventional GIC open laminate plus resin composite (n=8 for all groups and tests). Three tests were conducted to assess restorations: (A) inward cusp deflection during light curing, using DCDTs; (B) fracture strength using a ramped oblique load at 45° to the long axis in a servohydraulic testing machine in comparison with intact and unrestored teeth; (C) proximal marginal leakage using methylene blue dye and the effect of thermocycling. Data were analysed using 1-way ANOVA for cuspal deflection and fracture strength and Fisher's exact test for leakage. RESULTS: Laminate restorations resulted in significantly less cuspal deflection compared with resin composite (4.2±1.2 µm for RM-GIC and 5.1±2.3 µm for conventional GIC vs. 12.2±2.6 µm for composite, P<0.001). Fracture strength was not significantly different among all groups. Failure with all restorations was predominantly adhesive at the tooth-restoration interface. The two laminate groups showed significantly better marginal seal than composite alone, but sealing ability of conventional GIC deteriorated after thermocycling. CONCLUSIONS: Laminate restoration of root filled teeth had beneficial effects in terms of reducing cuspal deflection and marginal seal, with acceptable fracture strength.

Assessment of the quality of resin-dentin bonded interfaces: an AFM nano-indentation, µTBS and confocal ultramorphology study.

OBJECTIVE: The aim of this study was to assess by using confocal microscopy (CLSM), AFM nano-indentation and microtensile bond strength test (µTBS) the quality of the resin-dentin interfaces created with selected bonding parameters. METHODS: Dentin conditioned with H(3)PO(4) or EDTA was bonded in ethanol- or water-wet condition using a HEMA-free or HEMA-containing adhesive. The resin-bonded teeth were stored in distilled water (24h) and sectioned as match-sticks (0.9 mm(2)) for µTBS. Further resin-bonded teeth were sectioned and analyzed using CLSM, and AFM nano-indentation. The AFM imaging and nano-indentation processes were undertaken using a Berkovich diamond indenter. The modulus of elasticity (Ei) and hardness (Hi) across the interface were evaluated with the specimens in a fully hydrated status. The AFM imaging was performed both in dry and wet conditions for evaluating the shrinkage of the hybrid layer on dehydration. RESULTS: The HEMA-containing adhesive applied onto H(3)PO(4)-etched ethanol or water-wet dentin created hybrid layers with the lowest biomechanical nano-properties (p<0.05); no significant differences in µTBS were found between the two wet-bonding techniques (p>0.05). However, the ethanol-wet bonding reduced the dye penetration into the adhesive layer created with the HEMA-containing adhesive. Hybrid layers with high biomechanical properties, low micropermeability and no shrinkage were only possible when using HEMA-free adhesive applied in ethanol wet-dentin. In particular, a significant increase in Ei and Hi was achieved at the hybrid layer and underneath the resin-dentin interface of ethanol-wet EDTA-treated dentin. SIGNIFICANCE: The use of HEMA-free adhesives applied onto ethanol-wet dentin may be considered as an alternative and suitable bonding strategy to achieve high quality resin-dentin interfaces.