Variations in acid-etch patterns with different acids and etch times

Effect of etchant containing an Urushiol monomer from lacquer sap on dentin biostability and bonding performance

Objectives: This study aimed to evaluate the effectiveness of urushiol as an additive to surface acid etchant on dentin structure, by assessing the biostability of dentin, and determine the bonding strengths of dentin and enamel to the composite in the complicated oral microecology. Methods: Etchants with different concentrations of urushiol (0.5, 1, or 3 wt%) were formulated and tested for their bonding performance. Demineralized dentin beams that were etched with experimental etchants were incubated in simulated body fluid solutions by evaluating the weight decrement after 1 month. The effects of urushiol on dentin and matrix metalloproteinases were confirmed by scanning electron microscopy (SEM). Moreover, the antibiotic actions of urushiol on the common cariogenic bacteria Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii as well as the biofilm were evaluated, and its effect on bacterial morphology was observed by scanning electron microscopy. Finally, enamel and dentin specimens were prepared from human molars to determine the depth of demineralization by the etchants and the relationship with the resin bond strengths to enamel and dentin (μTBS) and the morphology of the bonding interface. Results: Urushiol could interact with dentine and inhibit collagenase activity, resulting in biostable dentine. The application of the etchants containing 0.5, 1, or 3 wt% urushiol significantly improved the durability of the dentin bonding interface with its instinctive antibacterial property (p < 0.05). Conclusion: Urushiol not only improves dentin stability by interacting with collagen and inactivating MMP activity but also plays a role in the antibacterial effects in the complicated oral microecology. The effectiveness of urushiol etchant prolongs the longevity of bonded dental restorations without compromising clinical operation time.

Scanning electron microscope analysis to evaluate the effect of pretreatment with ozone and sodium hypochlorite on pits and fissures of primary teeth

Introduction

The cornerstone of preventative therapy is made up of pit and fissure sealants and fluorides. Resin sealants have been shown to help reduce fissure decay in both primary and permanent teeth. Etching of primary molars is not effective due to prismless enamel, higher organic content, and diversity in fissure shape. Methods of pretreatment of pits and fissures have been hypothesized to promote microporosities in etched enamel and hence sealant adherence. Examining the etching pattern and surface roughness of the enamel surface can be used to gauge these.

Objective

This study aimed to evaluate the effect of pretreatment with ozone gas and 5.25% sodium hypochlorite solution on pits and fissures of primary teeth to check for the etching pattern and surface roughness.

Materials and Methods

Thirty noncarious primary molars were sectioned to retain the crowns, and randomly divided into three groups, sodium hypochlorite, ozone gas, and control. Each sample was pretreated with the agent, washed, followed by etching with 37% phosphoric acid. Samples were sectioned and subjected to scanning electron microscope analysis to evaluate the etching pattern and surface roughness.

Results

Comparison of the etching pattern in three groups showed a statistically insignificant difference (P=0.364). Surface roughness was highest in the hypochlorite group followed by ozone and control which showed a statistically significant difference (P = 0.001). The surface area between the three groups showed a statistically insignificant difference.

Conclusion

Sodium hypochlorite is a better pretreatment agent compared to ozone gas and acid etching alone. However, as all results were not statistically significant further research must be carried out to prove the effectiveness of these agents.

Effect of phytic acid on dentinal collagen solubilization and its binding and debinding potentials to dentin

OBJECTIVES

To study phytic acid (IP6) effect on collagen solubilization by assessing hydroxyproline (HYP) release, evaluate its binding to demineralized (DD) and mineralized dentin (MD) and determine the effect of different media on debinding of IP6.

METHODS

Demineralized dentin beams were incubated in 1%, 2% or 3% IP6 and HYP release was evaluated at 1 or 3 weeks and compared to those obtained in untreated control or phosphoric acid (PA)-treated beams. DD or MD powder was treated with 1%, 2% or 3% IP6 and the decrease in IP6 amount was quantitated by ultraviolet-visible spectroscopy. IP6-treated samples were re-suspended in distilled water, ethanol, urea or sodium chloride and the amount of IP6 displaced was determined.

RESULTS

At 1 week, the control group and IP6 showed lower HYP release when compared to PA (P < 0.05). There was no difference among PA, IP6 and control at 3 weeks (P = 0.22). IP6 binding was concentration dependent. 1% IP6 had higher binding potential with MD compared to DD while 2% IP6 showed the opposite result (P<0.05). 3% IP6 had similar binding values between DD and MD (P = 0.53). The highest debinding in MD occurred with urea for 2%, 3% and 1% IP6 in descending manner. Within each concentration of IP6 in DD, the highest debinding effect was reported with ethanol.

CONCLUSIONS

IP6 bound to DD and MD in a concentration-dependent manner. IP6 was debound from DD mostly by the action of ethanol, while in MD, urea caused the most displacement. Collagen solubilization of IP6-treated DD was comparable to untreated DD.

CLINICAL SIGNIFICANCE

These findings add to the potential use of IP6 as an alternative to PA for dentin etching which possibly results in long-term stability of resin-dentin adhesion.

Treatment of Moderately Crowded Teeth Using Lingual Fixed Appliance Prepared by a Modified HIRO® Technique: A Case Report and Method Description

There are various manual laboratory methods available for indirect positioning and bonding of lingual brackets. The manual setup has limitations because of its complicated laboratory procedures and requires time and specialized laboratory equipment. In addition, the manual method is also prone to human errors. In this case report, a description of a new method of laboratory preparation for the indirect bonding of lingual brackets is given by merging recent advances in digital dentistry with some of the ordinary manual steps in this field. Therefore, the well-known HIRO® technique has been modified by using the three-dimensional (3D) virtual setup instead of the traditional manual setup. This method does not require the use of any specialized laboratory equipment, and it is also cost-effective for patients who cannot afford fully customized lingual appliances. In this modified technique, 3Shape Ortho Analyzer™ software (3Shape, Copenhagen, Denmark) and a 3D printer (Prusa® i3 mk3; Prusa Research, Prague, Czech Republic) were used to align the teeth three-dimensionally into their desired positions and to produce the final working printed model on which lingual brackets were placed, and transfer caps were fabricated for clinical use.

Evaluation of developmentally hypomineralised enamel after surface pretreatment with Papacarie Duo gel and different etching modes: an in vitro SEM and AFM study

PURPOSE

This study aimed at investigating the surface morphology and nanotopography of normal enamel (NE) and developmentally hypomineralised enamel (HE) when subjected to various pretreatment protocols under scanning electron microscopy (SEM) and atomic force microscopy (AFM).

METHODS

Sixteen NE, 16 creamy/white (CW) HE and 16 yellow/brown (YB) HE specimens sectioned from extracted hypomineralised first permanent molars (FPMs) were included in this study. They were randomly distributed into 12 experimental groups (n = 4). Each group involved the following: (1) deproteinisation with Papacarie Duo^® gel or no deproteinisation, and (2) the use of Scotchbond™ Universal Adhesive (Scotchbond) in self-etch (SE) mode or 37% phosphoric acid etchant. Subsequently, the surface morphology and nanotopography of pretreated enamel specimens were evaluated under SEM and AFM, respectively.

RESULTS

SEM observation showed that deproteinisation with Papacarie Duo^® gel before phosphoric acid etching led to favourable etching patterns. This was consistent across all groups irrespective of the type of enamel specimen and the severity of hypomineralisation. In contrast, AFM results identified three factors that influenced surface parameters: (1) type of enamel specimen, (2) severity of hypomineralisation and (3) etching mode. YB HE recorded higher surface roughness values than CW HE and NE when subjected to the same pretreatment protocol. Deproteinisation and the application of Scotchbond in SE mode led to minimal topographic changes; however, acid etching was associated with an increase in surface roughness.

CONCLUSION

Deproteinisation with Papacarie Duo^® gel followed by acid etching contributed to improved etching patterns on HE.

Therapeutic properties of glass-ionomer cements: Their application to orthodontic treatment

Fluoride has been shown to be an effective agent in the prevention of caries during orthodontic treatment. Resin-modified glass-ionomer cements possess therapeutic anticariogenic properties acting as a fluoride reservoir and releasing fluoride into the environment, particularly at low pH where there is a threat of enamel demineralisation and white spot lesions (WSL's). Patient compliance to instructions in standard oral hygiene measures limits the success of caries prevention and the routine use of glass-ionomer cements can mitigate the lack of compliance, although RMGIC's are not a panacea against WSL's. The adhesion of GIC's to the enamel surface is a physicochemical bond rather than a mechanical bond which reduces the risk of iatrogenic damage to the enamel when bonding and debonding attachments. RMGIC's can be recommended as a bonding adhesive for all attachments but one needs to be selective when bonding molar attachments to avoid occlusal interferences as masticatory forces can be high in these areas.

Assessment of Wettability and Contact Angle of Bonding Agent with Enamel Surface Etched by Five Commercially Available Etchants: An In Vitro Study

Background

The quantity and quality of the etching pattern produced by acids play a significant role in the wettability and contact angle of the adhesive with the enamel surface in orthodontics. The better the etch pattern, the more the surface energy of the enamel, better the penetration of the adhesive, which ultimately results in better bond strength. The present study aimed to evaluate the contact angle of the bonding agent with the enamel surface etched by five commercially available etchants and check if any difference existed between the five.

Materials and Methods

Twenty-five human maxillary and mandibular central incisors and premolars extracted for orthodontic or dental purposes were used in this study as samples. The teeth were allocated into five groups based upon the etchant used to etch the enamel surface. After the samples were etched, a hard tissue microtome was used to create thin slices of the enamel surface. The samples were then exposed to bonding agent Ormco Enlight. The bonding agent was released in the form of droplets onto the enamel slices mounted on a contact angle goniometer. The contact angle values were tabulated, and statistical analysis using the one-way ANOVA test was carried out.

Results

The contact angle measurements of the etchant group, DPI, were the lowest, while D-tech has the highest contact angle values. However, statistical analysis revealed no statistically significant difference between the contact angle measurements of the five groups included in the study.

Conclusion

No statistically significant difference existed between the five etchant groups included in the study. However, commercially available etchant DPI showed lesser contact angle and thus better wettability in comparison to other groups. Further elemental analysis and surface analysis are required to validate these results.

Effect of Die Spacer Thickness on the Microshear Bond Strength of CAD/CAM Lithium Disilicate Veneers

Aim

The aim of this study was to compare the microshear bond strength of ceramic veneers with digital die spacer settings at 20, 40, and 100 µm.

Materials and Methods

Eighteen milled lithium disilicate microdiscs (IPS e.max CAD, Ivoclar Vivadent) were divided into three groups (n = 6) according to their digital die spacer settings: group A = 20 µm, group B = 40 µm, and group C = 100 µm. Six randomly selected sound maxillary premolars received three microdiscs each. Each microdisc was 1 mm in diameter and 1 mm in height. The buccal surfaces of the premolars were prepared with a 0.5 mm depth in enamel. After cementation, the specimens were thermocycled for 2,500 cycles between 5 and 55°C. Microshear bond strength testing was performed using a universal testing machine until bonding failure. Failure modes were evaluated using a stereomicroscope. Statistical analyses included one-way ANOVA, Tukey's post hoc test, and chi-square test with a 5% alpha error and 80% study power.

Results

The mean microshear bond strength values were calculated in MPa for group A = 31.91 ± 12.41, group B = 29.58 ± 5.03, and group C = 13.85 ± 4.12. One-way ANOVA (p ≤ 0.05) showed a statistically significant difference in microshear bond strength among the three groups. Tukey's post hoc test showed significant differences between groups A and C (p=0.004) and between groups B and C (p=0.011). The failure modes were presented as cohesive, adhesive, and mixed failures. Chi-square test indicated that the failure mode distribution was not significantly different among the three groups (p=0.970).

Conclusion

Higher digital die spacer settings decrease the microshear bond strength of CAD/CAM lithium disilicate veneers.

On the method of revealing enamel structure by acid etching. Aspects of optimization and interpretation

The study aimed at finding an optimal combination of acid concentration and etching time when nitric acid is used as etchant for the study of the finer details of human dental enamel structure. Four hundred 2-3-mm-thick segments of facio-lingually sectioned human third molar crowns were assigned to 20 groups with 20 specimens in each group, each group differing with respect to acid concentration (0.1, 1, 2.5, and 5%) and etching time (15, 30, 45, 90, and 180 s). After etching and preparation, specimens were observed in the scanning electron microscope (SEM). Surface roughness/topography increased with increasing acid concentration and increasing etching time, but not in a linear fashion; generally, prisms tended to go from flat-surfaced to cone-shaped and prism sheaths from fissure-like to wedge-shaped. Intragroup variations and intergroup similarities were considerable. The two major enamel factors determining the etch effect are crystal orientation and prism sheath properties. Other factors, such as distribution of porosities and crystal quality, also contribute probably. Slight to moderate topography is best for observing the finer enamel structure, for example, etching with concentrations in the range 0.1-1% and with etching times in the range 15-90 s, the stronger the acid, the shorter the time. The depth effect of nitric acid is judged to be relatively small. Considerable variations in expression of prism cross-striations were observed. SEM observations of acid-etched enamel in carefully selected planes are a powerful method for the study of enamel structure, bearing in mind the artifactual aspects of the observed surface.

Influence of phototherapy on bond strength and failure modes of enamel bonded to ceramic and metallic brackets with different surface treatment regimes

AIM

The aim of the current study was to assess efficacy of phototherapy on mode of failure and shear bond strength among different brackets in combination with dissimilar conditioning regimens on enamel surface.

MATERIAL AND METHODS

Ninety maxillary premolars were arbitrarily assigned into six groups (n = 15 each) based on surface conditioning of enamel. Group 1 and group 2 surface treated with total etch + rinse. Group 3 and group 4 surface conditioned with Er,Cr:YSGG. Group 5 and group 6 surface treated with self-etching primer (SEP). Now based on the type of bracket bonded to enamel surface. Group 1, 3 and 5 were bonded to metallic brackets (MB). Similarly, group 2,4,6 were bonded to ceramic bracket (CB). All samples from each group were positioned in a in a universal testing machine for shear bond strength testing. Ten samples from each group were used to discover the sites of bond failure using ARI with stereomicroscope. The mean shear bond strength of six groups were compared by analysis of variance (ANOVA) and pairwise comparison between groups were analysed with the Post hoc Tukey test at a significance level of (p < 0.05).

RESULTS

The maximum SBS values were displayed by group 1 total etch + rinse MB (14.84 ± 1.78) whereas the minimum shear bond strength values were exhibited by group 6 SEP CB (9.99 ± 0.91). Samples treated with total etch + rinse MB (14.84 ± 1.78) and group 3 Er,Cr:YSGG MB unveiled comparable bond strength (p > 0.05). Similarly, experimental group 2 total etch + rinse CB (12.52 ± 1.28) was found to be comparable to group 4 Er,Cr:YSGG CB (12.14 ± 4.12) (p > 0.05).

CONCLUSION

Enamel etched for bonding bracket with Er,Cr:YSGG phototherapy at (4.5 W and 30 Hz) displayed comparable bond strength to conventional Transbond XT independent on the type of brackets used.

Evaluation of Resin Penetration Depth in Enamel Surface for Orthodontic Bonding Exposed to Five Types of Enamel Conditioning Methods: A Scanning Electron Microscopic Study

Aims and Objectives:

To evaluate the enamel surface depth of resin penetration for orthodontic bonding when exposed to five types of enamel conditioning methods using scanning electron microscope.

Materials and Methods:

The sample comprised of 25 human extracted premolar teeth for orthodontic reasons. The samples are divided into 5 groups with each 5 teeth based on the enamel conditioning methods such as group A with 37% Phosphoric acid, group B with 10% Polyacrylic acid, group C with Self etch primer, group D with Laser etching and group E with air abrasion etching. All the samples in each group are bonded with metal brackets using Transbond XT Adhesive. After bonding, the teeth are sectioned mesiodistally using hard-tissue microtome and observed under scanning electron microscope at 500x and 3000x for the calculation of depth of resin penetration.

Results:

The teeth etched with 37%phosphoric acid exhibited significantly greater depth of resin penetration (15.1µm) than do self-etch and polyacrylic acid. Laser etching has comparable penetration depth with that of acid etching. Air abrasion has got the least penetration of all groups.

Conclusion:

Comparing the enamel treated with these conditioning methods, the penetration of resin material into enamel are greater when it is treated with 37% Phosphoric acid than self-etch or laser etching.

Partial Ceramic Crowns Prepared by Dental Students: Clinical Performance Up to Five Years

Partial ceramic crowns (PCCs) are an accepted treatment option for the restoration of posterior teeth with deficient tooth substance. Data on the survival of PCCs fabricated by dental students are scarce. The aim of this retrospective clinical study was to investigate the clinical performance and longevity of PCCs placed by dental students in the last year of their training program at the University of Basel, Switzerland. Eighty-eight patients who had received at least one PCC (n=108) in the program were considered for clinical assessment; their records were analyzed to detect previous complications or failures; and they were contacted by telephone. Criteria regarding aesthetic, functional, and biological aspects were rated with a scoring system from 1=clinically excellent to 5=clinically poor. The response rate was 66.3% (55 of 83 included patients), and 72.2% (n=78) of the PCCs were included in the analysis. Five PCCs had been lost within ten to 78 months after treatment. Six PCCs were recorded as failures (score 5), and ten received clinically unsatisfactory gradings (score 4). The risk of a clinically poor outcome was 14% after five years (86% survival), while the overall success rate was 63.5%. These results suggest that the clinical procedure of PCCs was successfully implemented by these students with satisfactory clinical survival.

Shear Bond Strength of Ceramic Brackets with Different Base Designs: Comparative In-vitro Study

INTRODUCTION

Knowledge about the Shear Bond Strength (SBS) of ceramic brackets with different base design is essential as it affects bond strength to enamel.

AIM

The aim of the present study was to evaluate and compare the effect of base designs of different ceramic brackets on SBS, and to determine the fracture site after debonding.

MATERIALS AND METHODS

Four groups of ceramic brackets and one group of metal brackets with different base designs were used. Adhesive precoated base of Clarity Advanced (APC Flash-free) (Unitek/3M, Monrovia, California), microcrystalline base of Clarity Advanced (Unitek/3M, Monrovia, California), polymer mesh base of InVu (TP Orthodontics, Inc., La Porte, IN, United States), patented bead ball base of Inspire Ice (Ormco, Glendora, California), and a mechanical mesh base of Gemini Metal bracket (Unitek/3M, Monrovia, California). Ten brackets of each type were bonded to 50 maxillary premolars with Transbond XT (Unitek/3M). Samples were stored in distilled water at room temperature for 24 hours and subsequently tested in shear mode on a universal testing machine (Model 3382; Instron Corp., Canton, Massachusetts, USA) at a cross head speed of 1mm/minute with the help of a chisel. The debonded interface was recorded and analyzed to determine the predominant bond failure site under an optical microscope (Stereomicroscope) at 10X magnification. One way analysis of variance (ANOVA) was used to compare SBS. Tukey's significant differences tests were used for post-hoc comparisons. The Adhesive Remnant Index (ARI) scores were compared by chi-square test.

RESULTS

Mean SBS of microcrystalline base (27.26±1.73), was the highest followed by bead ball base (23.45±5.09), adhesive precoated base (20.13±5.20), polymer mesh base (17.54±1.91), and mechanical mesh base (17.50±2.41) the least. Comparing the frequency (%) of ARI Score among the groups, chi-square test showed significantly different ARI scores among the groups (χ² = 34.07, p<0.001).

CONCLUSION

Different base designs of metal and ceramic brackets influence SBS to enamel and all were clinically acceptable.

Comparing orthodontic bond failures of light-cured composite resin with chemical-cured composite resin: A 12-month clinical trial

INTRODUCTION

In this clinical trial, we evaluated and compared bond failure rates of light-cured composite resin vs chemical-cured composite resin for 12 months.

METHODS

Twenty-two subjects (356 stainless steel brackets) were included in this study, and a split-mouth design was used to randomly allocate diagonally opposite quadrants to either chemical-cured (178 brackets) or light-cured (178 brackets) composite resin; the brackets came from the same manufacturer. The survival and failure rates of the brackets were evaluated by the mode of polymerization. The overall bracket survival rates were estimated using the Kaplan-Meier product limit estimate.

RESULTS

There were no significant differences in the bond failure rates between the chemical-cured and the light-cured composites (P = 0.52). Bond failures were greater in posterior teeth (6.7%) than in anterior teeth (1.2%). The highest failure rate was observed in the second premolars (7.7%).

CONCLUSIONS

The overall failure rate of brackets with the 2 bonding systems was 2.8%, which is acceptable for clinical use. The polymerization mode did not influence the bracket survival rate significantly.

Custom made profile projector: A new, innovative, and economical way to evaluation of tooth enamel loss after acid etching: An in vitro study

Introduction

Aim of this in vitro study is to evaluate the loss of tooth enamel after acid etching using a custom made profile projector (×100).

Materials and Methods

Twenty human extracted maxillary and mandibular premolars were collected, and each tooth was mounted on an acrylic block (2 cm × 1 cm) along with a 0.8 mm stainless steel wire partially embedded in acrylic in front of the buccal surface of the teeth. The 0.8 mm wire was used for reference; the image appeared on the projection screen was 80 mm implying that magnification ×100 has been achieved. Fabrication of custom made profile projector followed the principles of optics. Two projections of each sample before and after etching were projected. The projection was recorded using tracing paper. The difference between the two tracings before and after etching was measured using a millimeter scale. This reading was converted into microns, i.e., 1 mm = 10 μ.

Results

The statistical method used for this study is a measure of central tendency. The research shows that the average enamel loss was around 15.25 microns. The median is a value at the midpoint of the group, and median for enamel loss is 15 μ Mode for enamel loss is 15 μ that means most frequent or most repetitive enamel loss is 15 μ. The maximum enamel loss was 25 μ, and minimum of that was 10 μ.

Conclusions

The results of this study indicate that etching enamel with 37% phosphoric acid for 30 s loses 15 μ of surface enamel using an economical and efficient custom made profile projector.

Effect of multiple debonding sequences on shear bond strength of new stainless steel brackets

Objectives:

This in-vitro study aimed at evaluating the effect of three debonding sequences on the shear bond strength (SBS) of new stainless steel (SS) brackets.

Materials and Methods:

Stainless steel twin brackets (0.022-inch, American Orthodontics, Sheboygan, WI, USA) were bonded with light cure adhesive (Transbond XT, 3M Unitek, St. Paul, MN, USA) to 80 newly extracted human premolars after acid etching with 37% phosphoric acid (30 s). Brackets were debonded with a universal testing machine, and new brackets were bonded to teeth using the same adhesive and same manner. This process was repeated twice, and brackets were debonded within 24 h after bonding. The longitudinal changes of average SBS were assessed with the repeated measures ANOVA. Post-hoc tests using the Bonferroni correction were also used to compare the average SBS at three debonding sequences.

Result:

The mean SBS decreased significantly after each debonding sequence (P < 0.01). The corresponding mean values (standard deviation, 95% CI) after the first, second, and third debonding sequences were 22.88 MPa (4.08, 21.97-22.79), 19.36 MPa (4.54, 18.62-20.64), and 16.67 MPa (4.27, 15.72-17.62), respectively. There was no significant difference among the adhesive remnant index (ARI) scores of three debonding sequences (χ²= 5.067, df = 6, P = 0.53).

Conclusion:

Average SBS after three debonding sequences was significantly decreased, but was above the recommended 5.9-7.8 MPa. In-vivo studies are required to validate the finding of this study.

Effect of a self-etching primer and phosphoric acid etching on the bond strength of 4-META/MMA-TBB resin to human enamel

The purpose of this study was to evaluate the shear bond strength and durability of 4-META/MMA-TBB resin to human enamel. A self-etching primer that contained 4-META (Teeth Primer, TP) and 35-45% or 60-65% concentrations of phosphoric acid (K-Etchant Gel, KE, and Super Bond C&B Red Activator, RA) were used as the surface treatment agents. A methyl methacrylate (MMA)-based self-polymerizing resin (Super-Bond C&B) was used as a luting agent. The shear bond strength was determined both pre and post thermocycling. The results were statistically analyzed with a non-parametric procedure. The post-thermocycling shear bond strength of the TP group was significantly higher than that of other groups, and that of the KE group was significantly higher compared with the RA group. These results demonstrated that 4-META was effective. Furthermore, when the degree of tooth demineralization was compared, surface treatment with less demineralization using TP was the most effective treatment.

Improvement of enamel bond strengths for conventional and resin-modified glass ionomers: acid-etching vs. conditioning

OBJECTIVE

This study deals with the effect of phosphoric acid etching and conditioning on enamel micro-tensile bond strengths (μTBSs) of conventional and resin-modified glass ionomer cements (GICs/RMGICs).

METHODS

Forty-eight bovine incisors were prepared into rectangular blocks. Highly-polished labial enamel surfaces were either acid-etched, conditioned with liquids of cements, or not further treated (control). Subsequently, two matching pre-treated enamel surfaces were cemented together with one of four cements [two GICs: Fuji I (GC), Ketac Cem Easymix (3M ESPE); two RMGICs: Fuji Plus (GC), RelyX Luting (3M ESPE)] in preparation for μTBS tests. Pre-treated enamel surfaces and cement-enamel interfaces were analyzed by scanning electron microscopy (SEM).

RESULTS

Phosphoric acid etching significantly increased the enamel μTBS of GICs/RMGICs. Conditioning with the liquids of the cements produced significantly weaker or equivalent enamel μTBS compared to the control. Regardless of etching, RMGICs yielded stronger enamel μTBS than GICs. A visible hybrid layer was found at certain enamel-cement interfaces of the etched enamels.

CONCLUSIONS

Phosphoric acid etching significantly increased the enamel μTBSs of GICs/RMGICs. Phosphoric acid etching should be recommended to etch the enamel margins before the cementation of the prostheses such as inlays and onlays, using GICs/RMGICs to improve the bond strengths. RMGICs provided stronger enamel bond strength than GICs and conditioning did not increase enamel bond strength.

Bonding techniques in lingual orthodontics

Bonding techniques in lingual orthodontics differ slightly from their counterparts in labial treatment, although there are many shared features. If protocols are followed correctly, bonding outcomes are very predictable and lingual bracket bonding can be integrated into a mixed orthodontic practice with the minimum of disruption. Here, we highlight the fundamentals of both chemical and light/dual cure bonding procedures using lingual appliances, and discuss special bonding circumstances. Although not exhaustive, this article will provide essential information for those operators embarking on the bonding of lingual appliances.

Effect of lactic Acid etching on bonding effectiveness of orthodontic bracket after water storage

Objective. To determine the effect of lactic acid at various concentrations on the shear bond strength of orthodontic brackets bonded with the resin adhesive system before and after water storage. Materials and Methods. Hundred extracted human premolars were divided into 5 treatment groups and etched for 30 seconds with one of the following agents: lactic acid solution with (A) 10%, (B) 20%, (C) 30%, and (D) 50%; group E, 37% phosphoric acid (control). Metal brackets were bonded using a Transbond XT. Bonding effectiveness was assessed by shear bond strength after 24 hours and 6 months of water storage at 37°C. The data were analyzed with 2-way analysis of variance and Tukey's Honestly Significant Difference (HSD) test (α = .001). Results. Lactic acid concentration and water storage resulted in significant differences for brackets bond strength (P < .001). 20% lactic acid had significantly higher mean bond strength values (SD) for all conditions: 24 hours [12.2 (.7) MPa] and 6 months [10.1 (.6) MPa] of water storage. 37% phosphoric acid had intermediate bond strength values for all conditions: 24 hours [8.2 (.6) MPa] and 6 months [6.2 (.6) MPa] of water storage. Also, there were differences in bond strength between storage time, with a reduction in values from 24 hours and 6 months for all experimental groups (P < .001). Conclusion. Lactic acid could be used in place of phosphoric acid as an enamel etchant for bonding of orthodontic brackets.

Effect of fluoridated paste on the failure rate of precoated brackets bonded with self-etching primer: a prospective split-mouth study

INTRODUCTION

The aim of this prospective randomized clinical trial was to determine the effect of using fluoridated paste (Dentsply, York, Pa) compared with plain pumice (Ortho Technology, Tampa, Fla) on the clinical bond failure rates of precoated brackets bonded with self-etching primer.

METHODS

A split-mouth technique was used. The teeth in the maxillary right and mandibular left quadrants were prepared with a fluoridated paste only, and the teeth in the maxillary left and mandibular right quadrants were prepared with plain pumice before bonding the precoated brackets. A total of 627 brackets in 34 orthodontic patients (20 female, 14 male) were included in this study; 315 brackets were bonded after pumice treatment, and 312 were bonded after paste treatment. The patients were followed for 6 months to determine the rates of bracket failure.

RESULTS

The overall failure rate was 8%. The failure rates for pumice and paste were 4.8% and 11.2%, respectively. The McNemar test showed a statistically significant difference between the 2 groups. Based on tooth type, the failure rate of the maxillary canine and the mandibular central incisor brackets were significantly different for paste and pumice. There was also a difference in the survival rates of the brackets in both groups.

CONCLUSIONS

Preparation of the enamel surface with fluoridated paste before bonding with self-etching primer is not recommended. However, the use of plain pumice is recommended, even if it is time-consuming.

Characterization of the porosity of human dental enamel and shear bond strength in vitro after variable etch times: initial findings using the BET method

OBJECTIVES

(1) To quantitatively characterize human enamel porosity and surface area in vitro before and after etching for variable etching times; and (2) to evaluate shear bond strength after variable etching times. Specifically, our goal was to identify the presence of any correlation between enamel porosity and shear bond strength.

MATERIALS AND METHODS

Pore surface area, pore volume, and pore size of enamel from extracted human teeth were analyzed by Brunauer-Emmett-Teller (BET) gas adsorption before and after etching for 15, 30, and 60 seconds with 37% phosphoric acid. Orthodontic brackets were bonded with Transbond to the samples with variable etch times and were subsequently applied to a single-plane lap shear testing system.

RESULTS

Pore volume and surface area increased after etching for 15 and 30 seconds. At 60 seconds, this increase was less pronounced. On the contrary, pore size appears to decrease after etching. No correlation was found between variable etching times and shear strength. Samples etched for 15, 30, and 60 seconds all demonstrated clinically viable shear strength values.

CONCLUSIONS

The BET adsorption method could be a valuable tool in enhancing our understanding of enamel characteristics. Our findings indicate that distinct quantitative changes in enamel pore architecture are evident after etching. Further testing with a larger sample size would have to be carried out for more definitive conclusions to be made.

Effect of early orthodontic force on shear bond strength of orthodontic brackets bonded with different adhesive systems

INTRODUCTION

This study was conducted to evaluate the effect of applying early orthodontic force on the shear bond strength (SBS) of orthodontic brackets bonded with 4 adhesive systems.

METHODS

Eighty stainless steel brackets were bonded to the enamel surfaces of extracted premolars with 4 adhesive systems. For each adhesive, 10 brackets were bonded without application of force (groups 1, 3, 5, and 7), and another 10 were subjected to a 120-g force with a coil spring (groups 2, 4, 6, and 8). This force was applied 30 minutes after bonding and maintained for 24 hours. Groups 1 and 2 had Rely-a-bond primer and Rely-a-bond adhesive (Reliance Orthodontic Products, Itasca, Ill). Groups 3 and 4 had Transbond XT primer and Transbond XT adhesive (3M Unitek, Monrovia, Calif). Groups 5 and 6 had Transbond Plus Self Etching Primer and Transbond XT adhesive (3M Unitek). Groups 7 and 8 had RelyX Unicem (3M ESPE, Seefeld, Germany). After thermocycling, SBS testing was performed by using a universal testing machine (Type 500, Lloyd Instruments Ltd, Fareham Hants, UK). The results of SBS testing for all adhesives were analyzed by 2-way analysis of variance and the Duncan test. The unpaired Student t test was used to compare the effect of force on the SBS of each adhesive.

RESULTS

Transbond XT primer and its adhesive had the highest values (without force, 11.2 +/- 3.1 MPa; with force, 10.7 +/- 2.7 MPa), and RelyX Unicem had the lowest (without force, 5.8 +/- 1.5MPa; with force, 5.7 +/- 1.6 MPa). Application of force yielded nonsignificant reductions in SBS for all adhesives; this reduction was less pronounced with RelyX Unicem.

CONCLUSIONS

For all studied adhesive systems, orthodontic force up to 120 g can be applied within the first hour after bonding with no deleterious effects on bond strength.

In-vitro orthodontic bond strength testing: a systematic review and meta-analysis

INTRODUCTION

The aims of this study were to systematically review the available literature regarding in-vitro orthodontic shear bond strength testing and to analyze the influence of test conditions on bond strength.

METHODS

Our data sources were Embase and Medline. Relevant studies were selected based on predefined criteria. Study test conditions that might influence in-vitro bond strength were independently assessed by 2 observers. Studies reporting a minimum number of test conditions were included for meta-analysis by using a multilevel model with 3 levels, with author as the highest level, study as the second level, and specimens in the study as the lowest level. The primary outcome measure was bond strength.

RESULTS

We identified 121 relevant studies, of which 24 were included in the meta-analysis. Methodologic drawbacks of the excluded studies were generally related to inadequate reporting of test conditions and specimen storage. The meta-analysis demonstrated that 3 experimental conditions significantly affect in-vitro bond strength testing. Although water storage decreased bond strength on average by 10.7 MPa, each second of photopolymerization time and each millimeter per minute of greater crosshead speed increased bond strength by 0.077 and 1.3 MPa, respectively.

CONCLUSIONS

Many studies on in-vitro orthodontic bond strength fail to report test conditions that could significantly affect their outcomes.

The in vitro effect of repeated bonding on the shear bond strength with different enamel conditioning procedures

The aims of this study were to evaluate the effect on shear bond strength (SBS), adhesive remnant, and enamel surface of repeated bonding of new brackets on the same tooth using different methods of enamel conditioning. One hundred and thirty-five bovine incisors were used. Brackets were bonded to enamel using one of the following conditioning procedures: (1) 37 per cent phosphoric acid, (2) 37 per cent phosphoric acid (prior to first bond but not for further bonds), (3) Transbond Plus Self Etching Primer (TSEP), and (4) non-rinse-conditioner (NRC). Brackets were sequentially bonded and debonded three times following the same conditioning procedure with the exception of group 2 where 37 per cent phosphoric acid was not reapplied prior to the second and third bonding sequences. SBS and adhesive remnant were evaluated for each debond. Scanning electron microscopy observations were made for each conditioning sequence. Statistical analysis was undertaken using ANOVA, Mann-Whitney, and Kruskal-Wallis tests. Bond strength and adhesive remnant values were similar across the four groups for the first and second bonding sequences. At the third sequence, SBS was significantly less (P < 0.008) for group 2 (5.71 +/- 1.56 MPa) than for group 1 (9.42 +/- 2.75 MPa) and the adhesive remnant was significantly lower (P < 0.008) for group 2 (6.93% +/- 3.34) than for the other groups (group 1: 16.95 +/- 4.99 per cent, group 3: 14.40 +/- 5.11 per cent, and group 4: 14.60 +/- 5.33 per cent). When comparing the SBS and adhesive remnant of the three bonding/debonding sequences within each group, both the SBS and adhesive remnant for group 2 (SBS: 5.71 +/- 1.56 MPa and adhesive remnant: 6.93 +/- 3.34%) at the third sequence were significantly less (P < 0.017) than at the first (SBS: 10.44 +/- 3.55 MPa and adhesive remnant: 13.81 +/- 5.59%) and second (SBS: 9.23 +/- 2.69 MPa and adhesive remnant: 15.32 +/- 6.85%) sequences. Enamel changes were similar across all groups. TSEP and NRC produced bonds that were similar to acid etching. When acid etching is used, it is possible to avoid etching for a second bond but not for following bonds.

Bond strength comparison and scanning electron microscopic evaluation of three orthodontic bonding systems

This study sought to assess the efficacy of two self-etching primer systems (Transbond Plus and Beauty Ortho Bond) on orthodontic brackets. Therefore, shear bond strengths and bracket-adhesive failure modes (ARI scores) were determined and compared against an etch-and-rinse adhesive system (Transbond XT) under two experimental conditions (dry and saliva application). Shear bond strength test was performed at a crosshead speed of 0.5 mm/min, while enamel surfaces and enamel-adhesive interfaces were examined with SEM. There were no significant differences between Transbond XT (9.15 MPa) and Transbond Plus (9.74 MPa) under the dry condition, whereas that of Beauty Ortho Bond (6.47 MPa) was significantly lower than these two systems. Under SEM examination, both self-etching primers showed a milder etching effect and decreased depth of resin penetration into intact enamel than Transbond XT. In conclusion, results of this study showed that both self-etching systems seemed to offer more merits than conventional acid etching because of fewer irreversible changes to enamel.

Influence of environmental conditions on orthodontic bracket bonding of self-etching systems

The influence of temperature and relative humidity (RH) on the bond strength of orthodontic adhesives was investigated. Two self-etching/composite type, one acid-etching/composite type, and one acid-etching/PMMA type of adhesives were examined under different temperature and RH conditions. Orthodontic brackets were bonded to bovine enamel, and shear bond strength test was performed at a crosshead speed of 1.0 mm/min after 24-hour storage in 37 degrees C water. Data were analyzed by Tukey's HSD test. Each specimen was assigned an ARI score. All the materials tested exhibited their highest bond strength under room conditions at a range of 10.4-17.0 MPa. Conversely, when under a lower RH condition, bond strength for all the systems ranked the lowest within a range of 6.8-12.0 MPa, with bond failure at the bracket-adhesive interface. These results demonstrated that care should be exercised when using orthodontic adhesive systems in the oral environment.

Surface Analysis of Etched Molar Enamel by Gas Adsorption

Much research has been devoted to the study of etched enamel, since it is critical to bonding. Currently, there are no precise data regarding the etched-enamel specific surface area. The aim of this study was to characterize, by two different methods, the surface of human dental enamel in vitro after being etched. It was hypothesized that differences would be observed between specimens in terms of specific surface area and grade of etching. Sixteen third molar enamel samples were etched for 30 sec with 37% phosphoric acid prior to being viewed by SEM. Etched enamel surfaces were graded according to the Galil and Wright classification. The total surface area of etched samples was determined by the BET gas absorption method. A substantial variability in total surface area was observed between and among samples. A Pearson’s Correlation Coefficient showed a lack of relationship between etch pattern and total surface area.

A comparative evaluation of bracket bonding with 1-, 2-, and 3-component adhesive systems

INTRODUCTION

Today, 1- and 2-component adhesives are available for bracket bonding that could diminish the possibility of contamination during the bonding procedure and save the clinician chair-side time. Our aim in this study was to compare the shear bond strengths and the adhesive remnant index (ARI) scores of 1-, 2-, and 3-component adhesives after thermocycling.

METHODS

Fifty stainless steel brackets (10 per adhesive group) were bonded to extracted third molars with 5 adhesives. Group 1 was a 1-component adhesive, RelyX Unicem (3M Espe, Seefeld, Germany). Group 2 was a 1-component adhesive, Maxcem (Kerr, Orange, Calif). Group 3 was a self-conditioning 2-component adhesive system, Multilink (Ivoclar-Vivadent, Schaan, Liechtenstein). Group 4 was a 2-component adhesive system, Transbond Plus primer (self-etching) and Transbond XT adhesive (3M Unitek, Monrovia, Calif). Group 5 (control group) was a conventional 3-component adhesive system consisting of an etchant, Transbond XT primer, and XT adhesive (3M Unitek). All samples were thermocycled (6000 x 5 degrees C/55 degrees C) in a mastication device before shear bond strength testing and evaluation with the ARI.

RESULTS

No significant differences of shear bond strength between the 2- and 3-component adhesive systems were found. Significant decreases of shear bond strength were observed with 1-component adhesives, RelyX Unicem and Maxcem, compared with 2- and 3-component systems. The ARI scores indicated no significant differences between the groups.

CONCLUSIONS

With enhanced shear bond strength, 1- component adhesives have the potential to compete successfully with 2- or 3-component adhesives.

Scanning electron microscopic evaluation of enamel surfaces exposed to 3 orthodontic bonding systems

INTRODUCTION

This in-vitro study investigated the effects of conventional etching with a 35% phosphoric etching gel and priming/bonding with Transbond XT primer/adhesive (3M Unitek, Monrovia, Calif), conditioning with 10% polyacrylic acid and bonding with a resin-modified glass ionomer cement (Fuji ORTHO LC, GC Corporation, Tokyo Japan) or using a self-etching bonding system (Transbond Plus) and bonding with Transbond XT adhesive on the surface morphology of the enamel. The study was conducted at the Faculty of Dentistry, University of Oslo, in Norway, 2004.

METHODS

The enamel surfaces of extracted premolars where conditioned with 1 of the 3 systems and evaluated with environmental scanning electron microscope. Brackets were then bonded with 1 of 3 bonding agents and examined with a conventional scanning electron microscope.

RESULTS

The bonding systems induced different effects on the enamel structure. Phosphoric acid etching produced a rough, etched surface with the typical honeycomb pattern. Bonding brackets to such a surface resulted in thick resin tags relatively deep into the enamel. Less pronounced etching of the surface enamel was obtained by the self-etching primer system, and bonding resulted in smaller and fewer resin tags. The resin-modified glass ionomer bonded after conditioning the enamel with polyacrylic acid showed no resin tags.

CONCLUSIONS

Bonding systems with self-etching primers or conditioners with polyacrylic acid might offer potential benefits compared with conventional acid etching and priming because of fewer irreversible changes to the enamel surface.

Orthodontic materials research and applications: Part 1. Current status and projected future developments in bonding and adhesives

The purpose of this opinion article, to be presented in 2 parts, is to project immediate future developments expected in orthodontic materials research and applications. Analysis of the material is structured around 2axes: presentation of evidence summarizing the current status in various fields, and formulation of a hypothesis for short-term future developments. This first part of the article deals with advances and developments in bonding to enamel. Projected adhesive developments include greater use of high-energy lamps for polymerization in light-cured systems, universal application of molar tube bonding, widespread use of self-etching primers, broader acceptance of glass ionomers in their conventional and modified modes, and elimination of 2-phase adhesives in favor of no-mix and light-cured adhesives. Long-term future adhesive applications might also include biomimetic approaches, adopting mechanisms used by living organisms to adhere to surfaces.

Orthodontic bracket bonding: Enamel bond strength vs time

INTRODUCTION

Tests of bond strength between orthodontic brackets and enamel are generally conducted after at least 24 hours storage in water. However, debonding might occur soon after bracket placement during orthodontic treatment. We investigated the rate of bond strength development for orthodontic adhesives in bracket bonding.

METHODS

Four orthodontic adhesive systems were examined. Bovine incisors were mounted in self-curing acrylic resin, and the facial surfaces were wet-ground to expose flat enamel. Orthodontic brackets were bonded according to the manufacturers' instructions. Shear bond strengths were measured after storage in water for 5, 10, and 60 minutes, and 24 hours. Differences between bond strengths at 24 hours and the other test periods were statistically analyzed.

RESULTS

All materials tested had the highest bond strengths at 24 hours, and bond strength increased with storage time. The earliest time point at which there was no significant difference in bond strength compared with that at 24 hours was defined as the initial stable time. Differences in this value might have clinical implications for the assessment of orthodontic adhesives, which can incur high stresses immediately after placement.

CONCLUSIONS

The rate of development of enamel bond strength must be considered to ensure sufficient maturation of orthodontic adhesives before functional loading.

An in-vitro investigation into the use of a single component self-etching primer adhesive system for orthodontic bonding: a pilot study

OBJECTIVE

This pilot study assessed force to debond (N); time, and site of bond failure of a single component self-etching primer (SEP) and adhesive system, Ideal 1 (GAC International Inc., USA) and compared it with the conventional acid etch and rinse regimen using 37% o-phosphoric acid solution and either Transbond XT (3M Unitek) or Ideal 1 adhesive.

DESIGN

In vitro laboratory study.

SETTING

Bristol Dental Hospital, UK. Sept 2003-Sept 2004.

MATERIAL AND METHODS

Nine groups of 20 premolars were bonded using metal orthodontic brackets using three protocols: (1) 37% o-phosphoric acid etch and Transbond XT adhesive; (2) 37% o-phosphoric acid and Ideal 1 adhesive; (3) Ideal 1 SEP and Ideal 1 adhesive. Force to debond and locus of bond failure were determined at three time intervals.

RESULTS

Enamel pre-treatment prior to bonding, namely SEP versus conventional etching had no significant effect on the median force to debond with the Ideal 1 adhesive. Similarly, when the enamel was conventionally etched, the adhesive type, namely Ideal 1 or Transbond XT, had no significant effect on the measured force to debond. However, there appeared to be differences in the locus of bond failure: failure predominated at the enamel/adhesive interface for the Transbond XT conventional etch group and at adhesive/bracket interface for the Ideal 1 SEP and adhesive group and the Ideal 1 adhesive conventional etch group.

CONCLUSION

These results suggested that the complete Ideal 1 SEP and adhesive system might be successful in vivo leading therefore to a clinical trial. However, implications for clean up time are discussed and improvements to in vitro study designs are advised.

Self-etching primer and a non-rinse conditioner versus phosphoric acid: alternative methods for bonding brackets

The objective of this study was to evaluate the effectiveness of a self-etching primer, Transbond Plus Self Etching Primer (TSEP, 3M Unitek), and a non-rinse conditioner (NRC, Dentsply DeTrey) for bonding brackets, compared with the acid-etch technique. The brackets were bonded to extracted premolars using Transbond XT (3M Unitek). One of the following three conditioning protocols were used: (1) 37 per cent phosphoric acid (n = 25), (2) TSEP (n = 25), and (3) NRC (n = 15). Shear bond strength (SBS) was measured with a universal testing machine. The adhesive remaining after debonding was determined using image analysis equipment. Scanning electron microscope (SEM) observations were also carried out on 12 premolars to observe the enamel surfaces. No significant differences were observed in SBS between the three groups (P = 0.56). TSEP and NRC left significantly less adhesive on the tooth than the traditional acid-etch technique (P = 0.004 and P = 0.000, respectively). NRC left significantly less adhesive than TSEP (P = 0.001). SEM observations showed that NRC produced a less aggressive etch pattern than TSEP, and that the etching effect of TSEP approximated that of phosphoric acid.

Effects of salicylic-lactic acid conditioner on the shear bond strength of brackets and enamel surfaces

The purpose of this study was to evaluate the effects of salicylic-lactic (SL) acid conditioner on the shear bond strength of brackets. Fluoride releasing (Light-bond) and non-fluoride releasing (Enlight) composite adhesives were used after conditioning with 0.22% salicylic + 9% lactic acid or 34% phosphoric acid. Composite adhesives were light cured with either a halogen light curing (HLC) unit for 30-50 s or a plasma arc curing (PAC) unit for 4 s. The shear bond strength was measured with an Instron. Failure modes of debonded brackets were identified based on adhesive remnants on the bracket and tooth. Salicylic-lactic acid conditioning was found to provide adequate shear bond strength. Groups conditioned with SL acid were debonded mainly at the enamel-resin interface and comparatively clean enamel surface after debonding was observed than those conditioned with phosphoric acid. Using confocal laser scanning microscopic examinations, it was found that demineralization patterns between SL acid and phosphoric acid conditioned groups were not different when the same adhesive was used. The SL acid conditioner did not reduce the demineralization. Light-bond adhesive showed less demineralization than Enlight adhesive. The PAC unit can be recommended as an alterative to the HLC unit because it significantly reduces the irradiation time.

Effects of buccal versus lingual surfaces, enamel conditioning procedures and storage duration on brackets debonding characteristics

OBJECTIVES

To determine the influence of two enamel conditioning techniques on buccal and lingual tooth surfaces at two different times on debonding strength and tooth damage.

METHODS

The study included 50 premolars. Buccal and lingual surfaces of 10 teeth were scanned using SEM before (N=4) and after enamel conditioning by either acid etching or sandblasting prior to acid etching (N=6) for their morphology. The remaining 40 teeth were divided into 2 equal groups, differing in enamel conditioning prior to metallic bracket bonding on the buccal and lingual surfaces. Each group was equally subdivided into short-term (48h) or long-term (12m) water storage. Debonding strength was measured followed by SEM and EDAX for adhesive remnant index (ARI) and calcium remnant index (CRI) left on bracket bases. ANOVA with repeated measures was applied to the results.

RESULTS

The buccal enamel was rougher than the lingual one. The surface morphology after the two types of conditioning showed a different pattern. A significantly higher debonding strength was needed to debond the buccal brackets compared to the lingual ones (p<0.05). A significantly higher ARI (p<0.002) and higher CRI (p<0.005) were found in the lingual surface compared with the buccal. No differences were found in debonding strength ARI or CRI regarding the different conditioning or storage duration.

CONCLUSIONS

Lingual bonding leads to higher ARI and CRI than buccal bonding. Sandblasting prior to etching does not improve bonding strength for lingual or buccal bonding.

An in vivo investigation into bond failure rates with a new self-etching primer system

Self-etching primers have recently been introduced to simplify the orthodontic bonding process. The aim of this study was to compare the effectiveness of such a product with conventional 2-stage etching and priming with 37% o-phosphoric acid and a conventional unfilled primer. Twenty consecutive patients having orthodontic bonds placed were selected to participate in this cross-mouth control study. Diagonally opposite quadrants were randomly allocated to either the self-etching primer group or the conventional etching and priming group. A total of 364 teeth were bonded with a light-cured diacrylate adhesive; bond failures were then monitored over 6 months. There were 20 bond failures (10.99%) in the self-etching primer group and 9 bond failures (4.95%) in the conventional etch and priming group over this period. The results were analyzed with the McNemar test and 95% confidence interval. The difference between the failure proportions was -0.06 with an associated 95% confidence interval of -0.121 to 0.001. This study produced weak evidence to suggest that bond failures with a self-etching primer will be higher than those with conventional etching and priming. This increased likelihood of bond failure must be weighed against the time advantage of the self-etching primer when used at the initial bonding appointment.

Esthetic rehabilitation of anterior teeth affected by enamel hypoplasia: a case report

Alterations during tooth structure formation, mainly on anterior teeth, are known to severely compromise esthetics. This article presents a case report in which the etiology and clinical characteristics of anterior teeth affected by enamel hypoplasia are analyzed. The restoration treatment sequence is also discussed, demonstrating that the use of a hybrid and a microfilled composite associated with tooth hybridization (interdiffusing zone) can be used to conservatively rehabilitate a smile.

CLINICAL SIGNIFICANCE

This article presents a simple and conservative technique for restoring disfiguring areas of enamel hypoplasia to achieve an optimally esthetic result.