Enamel Conditioning Research Articles

Two-year randomized clinical trial of different restorative techniques in non-carious cervical lesions and MMP activity in gingival crevicular fluid

To evaluate different restorative techniques for non-carious cervical lesions (NCCLs) and the activity of matrix metalloproteinases (MMPs) in gingival crevicular fluid. Two hundred restorations were performed in 50 patients using resin composite restorative system without (I) and with selective enamel conditioning (II) and resin-modified glass-ionomer cement without (III) and with EDTA pretreatment (IV). Gingival crevicular fluid samples were collected in 15 patients. Restorations were evaluated using USPHS criteria at baseline and after 2years. Percentages of MMP activity were assessed by zymography as a surrogate outcome. Equality tests of two proportions, logistic regression analysis, survival analysis, ANOVA repeated measures, and Fisher tests were used. No differences in clinical performance were found among groups. Group I had lower retention at 2years than at baseline. Decreased alpha scores for marginal integrity and marginal discoloration were observed for all groups after 2years. MMP-2 decreased after 1year, and its activity increased back to the initial level after 2years, mainly for groups I, II, and III. MMP-9 increased after 1year, and it was reduced to the initial level after 2years, mainly for group I. All restorative techniques performed similarly in NCCLs after 2years with initial marginal defect alterations. MMP-2 reestablished its initial levels after 2years, and MMP-9 had few alterations over time in crevicular fluid. Clinical relevance The different restorative techniques are equally successful in NCCLs after 2years of clinical functioning and have similar effects on MMPs present in crevicular fluid.

Bond assessment of enamel conditioned with Er, Cr: YSGG laser and methylene blue photosensitizer activated by photodynamic therapy to orthodontic metallic brackets

AimTo assess bond integrity and failure mode after enamel pretreated with conventional and contemporary conditioning methods were bonded to metallic brackets (MB). Material and methodsForty maxillary central incisors were selected and disinfected. All specimens were mounted up to the cement-o-enamel junction and divided into four experimental groups randomly based on the enamel conditioning technique. Photodynamic therapy (PDT) was used to condition enamel in group 1, Total-etch and rinse (TER) was used to treat samples in group 2, Specimens in group 3 were conditioned with ECL, and samples in group 4 surface pretreated with SEP. Bonding of MB was performed on the surfaces of all the specimens with a Transbond XT. Specimens from all investigated groups were positioned on a universal testing machine maintaining buccal surfaces similar to the direction of the force. After bracket debonding bond failure was assessed using ARI. The bond integrity of all four groups was compared using analysis of variance (ANOVA). Post hoc Tukey test was used for pairwise comparison among different groups. ResultsGroup 2, TER+MB (15.38±0.14 MPa) displayed the highest bond value whereas the lowest values of SBS were exhibited by group 1, PDT+MB (10.11±0.17 MPa). The inter-group comparison revealed that specimens of group 2 and group 3, ECL+MB (14.61±0.55 MPa) demonstrated comparable bond strength (p>0.05). ConclusionEnamel conditioned with TER and ECL demonstrated comparable SBS. However, bond integrity after PDT and SEP (self-etch primer) surface treatment of enamel bonded with MB significantly lowered bond values.

Using self-etch adhesive agents with pit and fissure sealants. In vitro analysis of shear bond strength, adhesive remnant index and enamel etching patterns.

PurposeThe aim of this study was to evaluate in vitro, the shear bond strength (SBS) and adhesive remnant index (ARI) of pit and fissure sealants (PFS) after enamel conditioning with different new-generation self-etching (SE) agents; additionally, enamel etching patterns were assessed.MethodsHealthy unerupted third molars surgically removed for therapeutic reasons (n = 25p/g), were randomly assigned to six groups. Conventional etching (CE) or SE was applied prior to pit and fissure sealants bonding. Enamel conditioned surfaces were evaluated by SEM at × 500, × 1000, and × 2000 magnification to determine etching patterns. Subsequently, 25 PFS blocks (3 × 2 × 1.5 mm) p/g were bonded to enamel surface.Samples were stored in water at 37 °C for 24 h, previous to SBS and ARI test. One-way ANOVA and Tamhane statistic tests were used for SBS; while Mann–Whitney U and Kruskal–Wallis were employed for ARI (p ≤ 0.05).ResultsFor SBS test, CE_PFS_3M and SE1_PFS_Shofu groups showed the lowest values (8.74 ± 4.02 and 8.75 ± 3.90, respectively). The highest scores were observed in SE_PFS_Kuraray group (13.46 ± 5.83). Significant differences in SBS and ARI assessments were found. All experimental groups showed type 1 etching pattern.ConclusionThe etching pattern was less pronounced in self-etching groups, which showed an equal or superior in vitro performance compared to conventional etching agents. The clinical use of self-etching agents could be recommended before pit and fissure sealants application in new dental protocols. The best in vitro performance was observed when both applied materials, self-etching agent and pit and fissure sealant have 10-methacryloyloxydecyl dihydrogen phosphate in their chemical composition.

Observational Study Regarding Two Bonding Systems and the Challenges of Their Use in Orthodontics: An In Vitro Evaluation

The purpose of this in vitro study was to analyze and identify a methodology for the improvement of the shear bond strength of orthodontic brackets bonded with two orthodontic adhesive systems considered to be widely used, Transbond Plus Color Change with Transbond Plus Self-Etching Primer and Fuji Ortho LC with orthophosphoric acid under various enamel conditions: dry, moistened with water and moistened with saliva. The sample size included a group of 120 freshly extracted premolars distributed into six study groups, each one of 20 teeth. A universal testing machine was used to detach the brackets. We determined and compared the strength of the two studied adhesive systems used in different enamel surface conditions. The mean shear bond strength values in groups 1 (TPCC, TSEP, dry), 2 (TPCC, TSEP, water), 3 (TPCC, TSEP, saliva), 4 (Fuji Ortho LC, etched, dry enamel), 5 (Fuji Ortho LC, etched enamel, water) and 6 (Fuji Ortho LC, etched enamel, saliva) were 15.86, 12.31, 13.04, 15.27, 14.14 and 13.11 MPa, respectively. ANOVA test and Student’s t-test showed significant differences between groups. While clinically acceptable shear bond strengths were obtained for all six studied groups, a particular outcome that to the authors’ knowledge has not been documented elsewhere has been obtained: in case of water contamination, it is preferable to use Fuji Ortho LC instead of Transbond Plus.

Influence of reduced application time on bonding durability of universal adhesives to demineralized enamel.

This study aimed to assess the effect of application time on the microshear bond strength (μSBS) of three universal adhesives in demineralized and sound enamel before and after aging. Bovine teeth (192) were prepared where buccal surfaces were ground and divided into two groups (sound enamel and demineralized enamel). The specimens in each group were divided into 12 subgroups by combining 3 adhesive agents (All-Bond Universal, Scotchbond Universal, and Tokuyama Universal Bond) × 4 adhesion strategy. Each adhesive was applied with either prolonged (PA) or reduced (RA) application time in etch-and-rinse or self-etch mode. Bonded composites were subjected to μSBS testing after 24-h or 2-year water storage. The results were evaluated using four-way ANOVA and Tukey's post-hoc test (α = 0.05). The μSBS of adhesives to sound enamel in both etching modes was mostly similar to demineralized enamel, regardless of application time and aging time. At 24-h, all adhesives with PA in self-etch mode showed higher μSBS when compared with RA, except Tokuyama Universal Bond, but after 2-year aging, no significant difference was found in μSBS between RA and PA. The μSBS of adhesives with PA in etch-and-rinse mode depended on used adhesive and enamel condition compared to RA, regardless of μSBS testing time. PA of adhesives did not reveal a significant difference in μSBS to enamel, regardless of substrate type and etching mode. After 2-year aging, the bond strength of universal adhesives presented no significant difference between PA and RA treatments.

The Effect of Er:YAG Laser on a Shear Bond Strength Value of Orthodontic Brackets to Enamel-A Preliminary Study.

We sought to evaluate the effects of Er:YAG laser (LightTouch, LightInstruments, Israel) conditioning on enamel roughness and shear bond strength of orthodontic brackets on enamel. Eighteen human molars (n = 9) and premolars (n = 9), were divided into 3 groups depending on the enamel conditioning method; Er:YAG laser (G1, n = 6), conventional etching with 37% orthophosphoric acid (G2, n = 6), Er:YAG laser combined with conventional etching (G3, n = 6). Er:YAG laser parameters were as follows: energy: 100 mJ, frequency: 10 Hz, exposure time: 10 s, applicator diameter: 600 μm, fluence: 35.37 J/cm2, distance: 1 mm away from a tooth, cooling: 80%. An MTS 858 MiniBionix® machine was used to determine the shear bond strength (MTS System, Eden Prairie, MN, USA). The enamel structure was assessed using X-ray microtomography (SkyScan 1172, Bruker, Kontich, Belgium). The highest values of shear bond strength were obtained in the G3 group (9.23 ± 2.38 MPa) and the lowest values in the G2 group (6.44 ± 2.11 MPa) (p < 0.05). A significant change in the enamel surface was noted after applying laser, reaching up to 9% of enamel thickness, which was not observed in the etched samples. Moreover, the Er:YAG laser-irradiated enamel surface was characterized by the greatest roughness. The combined use of an Er:YAG laser with a conventional etching improves the adhesion of composite materials to the tooth.

Microleakage of pit and fissure sealings placed after enamel conditioning with phosphoric acid or with self-etching primers/adhesives.

BackgroundIt is still not fully understood what pretreatment is best for achieving maximum tightness for pit and fissure sealings (PFS).AimThis study investigated microleakage of PFS placed after etching with phosphoric acid or after the application of self‐etching primers/adhesives (SEPA).Design131 third molars were assigned to ten groups. In Hel‐P, Helioseal® was applied after phosphoric acid etching. In the other groups, SEPA were used (Dyr‐AP: Adper™ Prompt™ L‐Pop™, Dyract® Seal; Bea: BeautiSealant Primer and Paste; Hel‐Exp: Experimental primer, Helioseal®; Hel‐Cl: Clearfil™ SE Bond1, Helioseal®). Specimens were stored in distilled water at 37°C (28 days), followed by 3500 thermocycles and staining with 5% methylene blue (M) or 5% silver nitrate (S). After methylene blue staining and sectioning, microleakage was assessed light microscopically. During silver nitrate staining, specimens were dissolved by 32% HCl and remaining PFS were evaluated under a SEM.ResultsTightness, percentage of penetrated area, and maximum dye penetration were best for Hel‐P and Hel‐Cl (p < 0.05).ConclusionsPhosphoric acid etching of enamel and Clearfil™ SE Bond resulted in the best sealing quality. Methylene blue staining allowed the evaluation of more criteria (fissure shape, voids, sealant penetration depth) compared to silver nitrate.

Shear bond strength of APC Plus adhesive coated appliance system to enamel in wet and dry conditions: An in vitro study

It is claimed that a hydrophilic primer, called the moisture insensitive primer (MIP), can be used with both dry and wet enamel surfaces. This study sought to assess the shear bond strength (SBS) of APC Plus adhesive coated appliance system to enamel using MIP in wet and dry conditions. This in vitro experimental study evaluated 24 extracted maxillary premolars with intact buccal enamel. The teeth were randomly divided into two groups (n=12), and APC Plus premolar brackets were bonded to their buccal surface using moisture insensitive primer (MIP) under wet and dry enamel conditions. The SBS values were measured by a universal testing machine. The adhesive remnant index (ARI) score was also determined under a stereomicroscope. Data were analyzed using t-test and Mann-Whitney test at P<0.05 level of significance. The SBS in wet condition was significantly lower than that in dry condition (mean value of 18.37MPa versus 25.5MPa, P<0.001). The two groups had no significant difference regarding the ARI scores (P>0.05). However, in both groups, less adhesive was left on the tooth surface. This suggests that bond failure occurred at the adhesive-enamel interface. APC Plus adhesive coated appliance system in combination with hydrophilic MIP can be effective in clinical conditions with high risk of moisture contamination.

In vitro comparison of new generation adhesive systems in enamel conditioning with ER: YAG laser: SBS and ARI analysis

Bond strength which is as high as that of acid etching under in vitro conditions was provided by the laser which can be used more simply with a shorter clinical time than the acid etching. The aim of this study was to compare different orthodontic adhesives with the efficacy of Er: YAG laser for enamel conditioning. The effects of these adhesives’ types (single component orthodontic adhesives and glass carbomer cement) with lasers have not been studied previously. A total of 80 specimens were etched by irradiation of Er: YAG laser with 1.2-W power at 10 Hz and divided randomly into four groups (n = 20): group 1, bonding with Transbond XT primer with Transbond XT composite; group 2, Biofix; group 3, GC ortho connect; group 4; glass carbomer cement. Metal brackets were then bonded with adhesives. Shear bond strength tests were conducted on them in a universal testing machine after 24 h of water storage. A stereomicroscope was used to calculate the adhesive remnant index (ARI). The statistical analysis of the data was done. The mean and standard deviation of shear bond strength were 11.67 ± 3.22, 9.78 ± 3.68, 7.85 ± 1.90, and 5.06 ± 1.72 MPa in groups 1 to 4, respectively. According to the ARI scores, there was a main mixture of the bond failure modes in all groups. The optimal shear bond strength was yielded by Er: YAG lasers with the mentioned parameters, which may be used as another option for acid etching of the bracket bond to composite with single-component adhesive systems.

Influence of dental erosion on shear bond strength of ceramic brackets bonded with two different adhesive systems: an in vitro study

This study aimed to analyze the shear bond strength (SBS) of ceramic orthodontic brackets bonded with two different adhesive systems to intact and eroded teeth. Ceramic brackets were bonded to 72 bovine central incisors divided into four groups, defined by two study factors: enamel condition (control group, kept in artificial saliva; and experimental group, eroded by using immersion cycles in Coke™ for 90 seconds, every six hours for five days), and adhesive system type (Transbond™ XT or Transbond™ Plus Color Change). Polycrystalline ceramic brackets were adhesively fixed on all specimens using the same light curing protocol. SBS was tested using 0.5 mm/min and the failure mode was classified. SBS data was analyzed using two-way ANOVA followed by Tukey test. The adhesive remnant index (ARI) scores were analyzed using Kruskal-Wallis test with Dunn's post-hoc pairwise comparison (α=0.05). Percentages of ARI scores between the groups were compared by Fisher’s exact test. Spearman's correlation coefficient was applied to investigate the correlation between ARI scores and SBS values. Only the adhesive system factor had significant effect on SBS (p=0.014), Transbond™ Plus Color Change showing higher values. No significance was found for enamel condition (p=0.665) or the interaction between adhesive system and enamel condition (p=0.055). ARI scores frequencies differed between groups (p&lt;0.001). The median ARI scores were statistically different for most comparisons among the groups. However, no significant correlation was found between ARI scores and SBS. In conclusion, the type of adhesive system affected the SBS of ceramic brackets to dental enamel, but the enamel condition, intact or eroded, had no significant effect. There was no correlation between ARI scores and SBS values, although eroded enamel tended to retain more adhesive after bracket removal.

The paradigm of caries prevention remedies administration for pregnant women

The aim of this study is to improve the effectiveness of dental caries prevention in women during pregnancy due to the influence of kallikrein-4 gene polymorphism in mutation points G2664153A and G2142A on the state of tooth enamel. Materials and methods. The study involved 322 pregnant women of the European race registered in antenatal clinics in Omsk. The comparison group consisted of 261 non-pregnant patients of the same age who applied to a dentist for a planned sanitation or preventive examination. Patients of both groups underwent a study of the dental status, a study of the oral fluid, the distribution of the polymorphism of the kallikrein-4 gene in the mutation points G2664153A and G2142A was determined, and a statistical analysis of the results was carried out. The condition of the tooth enamel of pregnant women after a course of caries-preventive measures was assessed using an electrometric study. The degree of susceptibility of tooth enamel to demineralization processes and its ability to remineralize after application of a three-component calcium-fluorophosphate-containing gel in women of the comparison group was judged by the intensity of staining and the rate of disappearance of the focus of artificial demineralization of the enamel by performing the clinical assessment of enamel remineralization rate according to the T.L. Redinova et al. A survey and questionnaire survey of 52 dentists was also conducted regarding the effectiveness means of caries prevention in pregnant women. Results. Biologically significant links were established between the G/G, G/A and A/A polymorphisms of the KLK-4 gene and clinical indicators of the intensity and rate of caries growth. The study substantiated the optimal means of caries prevention — a three-component calcium-fluorophosphate-containing gel, and the electrical conductivity of tooth enamel confirmed its clinical efficacy in pregnant women of different ages.

Effect of Nd:YAG and Er:YAG laser tooth conditioning on the microleakage of self-adhesive resin cement

Statement of problem Recently, the application of lasers in restorative dentistry has been considered for cavity preparation and surface conditioning of enamel and dentin. However, the beneficial effects of cavity surface conditioning by laser irradiation on microleakage are still controversial. Purpose This study aimed to compare the microleakage of self-etch adhesive resin cement with Nd:YAG and Er:YAG laser tooth surface conditioning to evaluate the capabilities of these lasers as a reliable replacement for etching cavities. Materials and methods Fifty-four class V cavities were prepared on the buccal and lingual surfaces of 27 sound human premolar teeth. The samples were randomly divided into three groups (n = 18): group 1: no conditioning; group 2: conditioned with Er:YAG laser (2940 nm, 10 Hz, 1.2 W); group 3: conditioned with Nd:YAG laser (1064 nm, 1.5 W, 10 Hz). All the cavities were filled with self-adhesive resin cement. After curing and polishing, the samples were immersed in 2% methylene blue solution for 24 h, and after being embedded in acrylic resin, they were sectioned longitudinally and examined under a stereomicroscope. The data were submitted to Kruskal–Wallis and Dunn tests (α = 0.05). Results The lowest microleakage mean rank was observed in the Er:YAG group (19.19), and the highest mean rank was noted in the Nd:YAG group (33.08), with significant differences between the three groups (P-value = .01). Pairwise comparisons demonstrated significant differences between the Er:YAG and Nd:YAG groups (P-value = .004) as well as Er:YAG and no conditioned groups (P-value =.022). Conclusion The irradiation of the Er:YAG laser (2940 nm, 10 Hz, 1.2 W) on cavity surface resulted in less marginal microleakage of self-etch adhesive resin cement restorations compared to Nd:YAG (1064 nm, 1.5 W, 10 Hz) and no conditioning groups.

Three-year evaluation of different adhesion strategies in non-carious cervical lesion restorations: a randomized clinical trial.

:Objective:To evaluate non-carious cervical lesions (NCCLs) restored with different adhesion strategies.Methodology:This is a prospective, randomized, double-blind, split-mouth study. An adhesive restorative system (Single Bond Universal/Filtek Z350XT – SBU) was evaluated both without and with selective enamel conditioning (E-SBU), resin-modified glass-ionomer cements (Vitremer; RMGIC), and ethylenediaminetetraacetic acid pretreatment (EDTA; E-RMGIC). In total, 200 restorations, placed in 50 patients, were evaluated at baseline and at a 3-year follow-up using the modified United States Public Health Service (USPHS) criteria. Data were analyzed using the two-proportion equality test, multinomial logistic regression, Wilcoxon test, and Kaplan-Meier survival curves.Results:In total, 42 (84%) patients returned for the 3-year follow-up. SBU showed restoration losses statistically different from RMGIC. Retention was also statistically different in SBU between baseline and the 3-year follow-up. Marginal defects and surface texture were statistically significant for all groups in the period studied, except for the surface texture of SBU and the marginal integrity in E-RMGIC. We observed no statistically significant difference in wear, secondary caries, anatomical form, surface staining, and color over time. Recession degree was the only factor to influence retention rates. Cumulative survival (%) was 89, 98, 98, and 95.3, for SBU, SE-SBU, RMGIC, and E-RMGIC, respectively, without significant differences among them. There was a statistically significant difference between survival curves; however, multiple comparison procedures found no statistical differences.Conclusion:Selective enamel etching affected the retention of non-carious cervical restorations. Adhesion using EDTA and resin-modified glass-ionomer cements delayed marginal defects over time. The degree of gingival recession influenced retention rates. Resin composite restorations showed initial marginal defects, and ionomer restorations, reduced surface luster. EDTA pre-treatment followed by resin-modified glass-ionomer cements may be a promising adhesion strategy for NCCL restorations.

Dental enamel structure in long-nosed armadillos (Xenarthra:Dasypus) and its evolutionary implications

AbstractMost xenarthrans have a reduced and simplified dentition that lacks enamel. However, the presence of prismatic enamel has been recorded in the Eocene armadillos Utaetus buccatus (Euphractinae) and Astegotherium dichotomus (Astegotheriini). Among extant xenarthrans, the occurrence of enamel has been recognized only in the long-nosed armadillo, Dasypus novemcinctus (Dasypodinae), but its microstructure has never been described. In this contribution, we analyse the enamel microstructure in deciduous and permanent teeth of four Dasypus species. In deciduous molariform teeth of some species, we identify an apical cap of vestigial enamel (without crystalline structure), interpreted as an amorphous ameloblastic secretion. In permanent teeth, a thin layer of true enamel is found in the apical portion of unworn molariforms. The enamel is prismatic in D. novemcinctus, but in Dasypus hybridus, Dasypus sabanicola and Dasypus punctatus it is prismless. Taking into account the Eocene species of armadillos, the ancestral condition of enamel in cingulates could have been more complex (as in other placentals) and undergone progressive reduction, as shown in the Dasypus lineage. In light of previous genetic and developmental studies, we review and briefly discuss the processes that can account for the reduction/loss of enamel in extant and extinct armadillos. The retention of enamel and the fact that this genus is the only living xenarthran with two functional generations of teeth support the early divergence of the Dasypus lineage among living cingulates. This is in agreement with morphological and molecular analyses.

In Vitro Shear Bond Strength of Orthodontic Brackets after Enamel Conditioning with Acid Etching and Hydroabrasion.

The purpose of this study was to evaluate the shear bond strength and adhesive remnant index ARI) of orthodontic brackets following enamel conditioning with acid etching, hydroabrasion, and with both procedures. Thirty extracted human premolars were divided into three groups and received either acid etching, hydroabrasion or both procedures. Orthodontic brackets were bonded with composite resin. Shear bond strength was tested with a tensile machine, then the teeth were observed under a stereomicroscope to evaluate ARI scores. The enamel morphology after each conditioning method was evaluated with scanning electron microscope imaging. A one-way ANOVA and a Kruskal−Wallis H test were used to compare the bond strength and the ARI scores among the three groups. Hydroabrasion alone produced shear bond strength values below clinical acceptability, while the combination of acid etching and hydroabrasion produced the highest values. The ARI scores in the hydroabrasion group were significantly different from the other groups. Hydroabrasion followed by acid etching was effective in increasing the shear bond strength of orthodontic brackets. Further in vivo studies are needed to confirm the cost and benefits of this technique.

English

English

In Vitro Evaluation of Different Protocols for Preventing Microleakage of Fissure Sealants Placed Following Saliva Contamination.

To evaluate the effect of different enamel conditioning protocols and their re-application on the microleakage of fissure sealants placed following saliva contamination. The study included 156 human third molars in 16 subgroups (2×4×2) under two main groups (sealant type): Group A- hydrophobic resin sealant, 3M Clinpro™ Sealant; Group B- hydrophilic resin sealant, Ultraseal XT Hydro. Each group was then divided according to the type of surface conditioning; 1- Er,Cr:YSSG laser etching, 2- acid-etching, 3- acid-etching+etch-and-rinse adhesive (Prime&Bond® One Select) and 4- self-etching adhesive (Clearfil™ SE Bond). After contaminating the conditioned occlusal enamel surfaces with artificial saliva, fissure sealant was applied in half of the specimens (a), whereas in the other half, (b) the respective surface conditioning was repeated and then fissure sealant was placed. Following thermocycling, the samples were immersed in basic fuchsin, sectioned, and dye penetration was quantitatively assessed with ImageJ. Two-way ANOVA and Bonferroni post-hoc tests were used for statistical analyses (p<0.05). The least microleakage was observed in A3b and A3a, whereas B4b and B4a were the subgroups with the highest microleakage. Following saliva contamination, when surface conditioning was not re-applied, the effects of fissure sealant types and surface conditioning were significant (p=0.005 and p<0.001, respectively). However, their interaction was insignificant (p=0.173). When surface conditioning was re-applied after saliva contamination, the effects of type of fissure sealant and surface conditioning (p=0.000, for both) and their interaction (p=0.004) were significant. 3M Clinpro™ Sealant was superior to Ultraseal XT Hydro. Re-application of Er,Cr:YSSG laser and the self-etching adhesive did not affect the microleakage of both fissure sealants. Without re-application, acid-etching+etch-and-rinse adhesive was superior to acid-etching only. However, both of them were similarly successful when they were re-applied following saliva contamination.

Effect of Acid Etching and Er:YAG Laser Enamel Conditioning on the Microleakage of Glass Carbomer Fissure Sealants

Objective: This study aimed to evaluate the effects of Er:YAG laser used alone or in combination with acid etching as surface conditioners on the microleakage of a glass carbomer fissure sealant for permanent molar teeth.

Performance of novel enamel-conditioning calcium-phosphate pastes for orthodontic bonding: An in vitro study.

This study aimed to develop remineralizing calcium-phosphate (CaP) etchant pastes for enamel conditioning before bracket bonding and evaluate the bonding performance, failure pattern, and enamel surface integrity post bracket debonding in comparison with the conventional phosphoric acid (PA) etchant gel. Micro-sized monocalcium phosphate monohydrate and hydroxyapatite (micro- and nano-sized) powders were mixed with various phosphoric and nitric acid concentrations to develop eight acidic CaP pastes. Ninety extracted human premolars were randomly assigned into eight experimental and one control group (n=10). The developed pastes and control (commercial 37% PA-gel) were applied onto the enamel using the etch-and-rinse protocol before bonding metal brackets. Shear bond strength and adhesive remnant index (ARI) scores were evaluated after 24 hours water storage (24 h) and post 5000 thermocycling (TC). Field emission scanning electron microscopy (FE-SEM) was used to evaluate enamel damage after bracket debonding. The developed CaP pastes, excepting MNA1 and MPA1, resulted in significantly lower SBS values and ARI scores than 37% PA gel. Etching with 37% PA yielded roughened, cracked enamel surfaces with excessive retention of adhesive residue. In contrast, enamel treatment with the experimental pastes exhibited smooth, unblemished surfaces, with obvious CaP re-precipitation induced by mHPA2 and nHPA2 pastes and to a lesser extent by MPA2 paste. Three newly developed CaP etchant pastes (MPA2, mHPA2, and nHPA2) can be promising alternative enamel conditioners that outperform conventional PA by generating adequate bracket bond strengths besides precipitating CaP crystals on the enamel. Moreover, these pastes maintained unblemished enamel surfaces with no or minimal adhesive residue after bracket removal. Key words:Enamel Conditioning, Calcium Phosphate, Bracket Bond Strength, Orthodontic Bonding, enamel damage.

Dental Caries, Developmental Defects of Enamel and Enamel Microhardness Associated with Genetic Polymorphisms in the RANK/RANKL/OPG System.

Purpose: Recent studies have suggested that disruptions in the RANKL/RANK/OPG system might be involved in enamel conditions. The aim of this study was to test whether genetic polymorphisms in RANK, RANKL and OPG are associated with dental caries, developmental defects of enamel (DDE) and enamel microhardness. Study design: Saliva samples were collected from two subsets for the purpose of genomic DNA extraction. In the first subset, composed of 248 children, dental caries and DDE were evaluated during their clinical examination. In the second subset, composed of 72 children, enamel samples from the buccal surface of primary teeth were used for enamel microhardness analysis. Genetic polymorphisms in RANK, RANKL and OPG were genotyped by real-time polymerase chain reactions in all samples from both populations. The chi-square test was used for dental caries and DDE analysis while, one-way ANOVA with Tukey's post-test was used for microhardness analysis. Hardy-Weinberg equilibrium was also calculated. The established alpha was 5%. Results: Caries experience analysis demonstrated a statistically-significant difference for OPG allele distribution in primary dentition (p=0.033). The studied polymorphisms in RANK, RANKL and OPG were not associated with DDE or enamel microhardness (p>0.05). Conclusion: The genetic polymorphism rs2073618 in OPG is associated with dental caries experience in primary dentition.