Influence of a simulated oral environment on microleakage of two adhesive systems in Class II composite restorations

Dentin adhesives application deviations: Effects on permeability and nanoleakage

The purpose was to evaluate the effect that deviations from the recommended protocol of a two-step etch-and-rinse adhesive system has on permeability and nanoleakage. One hundred and twenty dentin disks were treated with a two-step etch-and-rinse adhesive system, according to the manufacturer's instructions, or using five simulated deviations from the recommended protocol: applying potassium oxalate, reducing the application time of the adhesive, avoiding adhesive drying, aggressively drying the adhesive, and double application of adhesive. Kruskal-Wallis and Tukey's post hoc comparisons were used to evaluate the permeability reduction (α=0.05). Twelve additional dentin disks were prepared for transmission electron microscope (TEM) analysis of nanoleakage. Aggressive drying, adding additional layers of adhesive or using oxalate reduced dentin permeability and yielded a better infiltration of the hybrid layer, whereas reducing the application time or less drying the adhesive did not to reduce dentin permeability, caused extensive nanoleakage, showing immediate compromised dentin sealing.

In Vitro Zinc-Air Battery Evaluation for Use in Intraoral Medical Devices

The aim of the present work was to evaluate the possibility of using zinc-air batteries in intraoral medical devices. We analyzed the electrical behavior of zinc-air batteries when submitted to different levels of temperature, humidity, and limited quantities of air. The experimental setup was divided in three different parts. Firstly, a set of batteries were tested within a climatic chamber and subjected to discharging tests similar to those recommended by the manufacturer. The climatic chamber allowed an accurate variation of humidity and temperature. Secondly, the batteries were placed in a small prototype of intraoral medical device and tested in the absence of air. Lastly, we used a robot arm to repeatedly immerse the prototype in artificial saliva. The results obtained demonstrated the viability of zinc-air batteries as a power solution for intraoral medical devices, as they tolerate high levels of humidity and are capable of working with limited quantities of air. In addition, this kind of battery presents a volume to electrical capacity ratio more than three times higher than lithium batteries, which may open important improvement for powered medical devices.

Microleakage of Nanofilled Resin-modified Glass-ionomer/Silorane- or Methacrylate-based Composite Sandwich Class II Restoration: Effect of Simultaneous Bonding

Objectives

Microleakage of composite restorations at the cervical margin placed apically to the cementoenamel junction (CEJ) is still a concern. This study evaluated the effect of simultaneous bonding application on cervical sealing of nano-ionomer/silorane- or methacrylate-based composite open sandwich Class II restorations in the modified technique compared with that of conventional bonding.

Methods and Materials

In 60 sound maxillary premolars, two standardized Class II cavities were prepared with cervical margins 1 mm below the CEJ. The teeth were randomly divided into six groups of 10 teeth each. In the first three groups (groups 1-3), Clearfil SE Bond and Clearfil APX (Kuraray) were used for restoration in the total bonding technique (group 1), conventional open sandwich technique associated with a nano-ionomer (Ketac N100, 3M ESPE) (group 2), and modified open sandwich technique with simultaneous bonding application for both nano-ionomer and composite (group 3). In the second three groups (groups 4-6), Silorane Adhesive and Filtek Silorane composite (3M ESPE) were used in the same manner as in the first three groups, respectively.

Results

The simultaneous bonding application in the modified sandwich restorations (with SE Bond or Silorane Adhesive) resulted in a significant reduction of the cervical microleakage compared with that of the conventional bonding (p<0.05). However, microleakage of the modified technique was similar to that of the total bonding (with SE Bond or Silorane Adhesive) (p>0.05), both showing good marginal seal.

In Vitro Performance of Class I and II Composite Restorations: A Literature Review on Nondestructive Laboratory Trials—Part I

Posterior adhesive restorations are a basic procedure in general dental practices, but their application remains poorly standardized as a result of the number of available options. An abundant number of study hypotheses corresponding to almost unlimited combinations of preparation techniques, adhesive procedures, restorative options, and materials have been described in the literature and submitted to various evaluation protocols. A literature review was thus conducted on adhesive Class I and II restorations and nondestructive in vitro tests using the PubMed/Medline database for the 1995-2010 period. The first part of this review discusses the selected literature related to photoelasticity, finite element analysis (FEM), and microleakage protocols. Based on the aforementioned evaluation methods, the following parameters proved influential: cavity dimensions and design, activation mode (light or chemical), type of curing light, layering technique, and composite structure or physical characteristics. Photoelasticity has various limitations and has been largely (and advantageously) replaced by the FEM technique. The results of microleakage studies proved to be highly inconsistent, and the further use of this technique should be strictly limited. Other study protocols for adhesive Class II restorations were also reviewed and will be addressed in part II of this article, together with a tentative relevance hierarchy of selected in vitro methods.

Clinical evaluation of self-etch and total-etch adhesive systems in noncarious cervical lesions: a two-year report

OBJECTIVE

The purpose of this study was to compare the clinical performance of two self-etch dental adhesives with Single Bond Plus, a traditional one-bottle total-etch dental adhesive, for the restoration of noncarious cervical lesions.

MATERIALS AND METHODS

A total of 156 restorations were placed in noncarious cervical lesions with a minimum depth of 1.5 mm. Patients had no chronic periodontal disease and had normal salivary function. Each patient received restorations on three teeth, each bonded with either Adper Single Bond Plus, Adper Easy Bond, or Adper Scotchbond SE dental adhesive. All lesions were restored with Filtek Supreme Plus composite resin. All teeth were isolated with a rubber dam, received a short enamel bevel, and were cleaned with flour of pumice. The adhesives and resin composite were applied following the manufacturers' instructions. Restorations were clinically evaluated at baseline, six months, one year, and two years using modified US Public Health Service criteria.

RESULTS

Two-year retention was recorded as 97.3%, 90.5%, and 95.2%, for Single Bond Plus, Scotchbond SE, and Easy Bond, respectively. Statistical analysis did not show a significant difference (p>0.05) in clinical performance between any of the three adhesives after a period of two years.

A 12-month clinical evaluation of pit-and-fissure sealants placed with and without etch-and-rinse and self-etch adhesive systems in newly-erupted teeth

Objectives

The objective of this one-year clinical study was to investigate the effect of two adhesive systems (Adper Single Bond, a two-step etch-and-rinse and Clearfil SE Bond, a two-step self-etch system) on pit-and-fissure sealant retention in newly-erupted teeth. This study compared the success of the sealants in mesial and distopalatal grooves with and without these two adhesive systems.

Material and Methods

In a clinical trial, 35 children aged 6-8 years undergoing sealant placement were recruited. This one-year clinical study scored 70 mesial and 70 distopalatal sealants of newly-erupted permanent maxillary first molar, with a split-mouth design. All children received sealant alone in one permanent maxillary molar tooth. Children were randomized into two groups. One group received Self-Etch (SE) bond plus sealant and the other group received Single Bond plus sealant in another permanent maxillary molar tooth. Clinical evaluation at 3, 6 and 12 months was performed and the retention was studied in terms of the success and failure.

Results

The success rate of sealant in the distopalatal groove, using SEB at 3, 6 and 12 months was 93.3% (95% CI: 68.0, 99.8), 73.3% (95% CI: 44.9, 92.2) and 66.7% (95% CI: 38.4, 88.2), respectively. It was greater than that of the distopalatal groove in SB group with a success rate of 62.5% (95% CI: 35.4, 84.8), 31.3% (95% CI: 11.8, 58.7) and 31.3% (95% CI: 11.8, 58.7), at the three evaluation periods. The success rate of sealant in the mesial groove using SEB was 86.6% (95% CI: 59.5, 98.3), 53.3% (95% CI: 26.6, 78.7) and 53.3% (95% CI: 26.6, 78.7), while this was 100% (95% CI: 79.4, 100.0), 81.3% (95% CI: 54.4, 96.0) and 81.3% (95% CI: 54.4, 96.0) using SB, at 3, 6 and 12-month evaluation periods.

Conclusions

These results support the use of these two bonding agents in pit-and-fissure sealants under both isolated and contaminated conditions. Further, SE bond seemed to be less sensitive to moisture contamination.

Effects of three restorative techniques in the bond strength and nanoleakage at gingival wall of Class II restorations subjected to simulated aging

OBJECTIVE

To evaluate the effects of simulated aging in bond strength and nanoleakage of class II restorations using three different restorative techniques.

MATERIALS AND METHODS

Class II preparations (n = 12) were restored using: FS - composite resin Filtek Supreme Plus (3M/ESPE); RMGIC + FS - resin-modified glass ionomer cement Vitrebond Plus (3M/ESPE) + FS; and FFS + FS - flowable composite resin Filtek Supreme Plus Flowable (3M ESPE) + FS. The teeth were assigned into two groups: Control and Simulated Aging - Thermal/Mechanical cycling (3,000 cycles, 20-80 °C/500,000 cycles, 50 N). From each tooth, two slabs were assessed to microtensile bond strength test (μTBS) (MPa), and two slabs were prepared for nanoleakage assessment, calculated as penetration along the restoration margin considering the penetration length (%) and as the area of silver nitrate particle deposition (μm(2)). Data were analyzed by two-way analysis of variance (ANOVA) followed by Tukey's post hoc test (p < 0.05).

RESULTS

FS presented the highest μTBS to dentin (22.39 ± 7.55 MPa) after simulated aging, while the presence of flowable resin significantly decreased μTBS (14.53 ± 11.65 MPa) when compared to no aging condition. Both control and aging groups of RMGIC + FS presented the highest values of silver nitrate penetration (89.90 ± 16.31 % and 97.14 ± 5.76 %) and deposition area (33.05 ± 12.49 and 28.08 ± 9.76 μm(2)). Nanoleakage was not affected by simulated aging.

CONCLUSIONS

FS presented higher bond strength and lower nanoleakage and was not affected by simulated aging. Use of flowable resin compromised the bond strength after simulated aging.

CLINICAL RELEVANCE

The use of an intermediate layer did not improve the dentin bond strength neither reduced nanoleakage at the gingival margins of class II restorations under simulated aging conditions.

Prediction and diagnosis of clinical outcomes affecting restoration margins

The longevity of dental restorations is largely dependent on the continuity at the interface between the restorative material and adjacent tooth structure (the restoration margin). Clinical decisions on restoration repair or replacement are usually based upon the weakest point along that margin interface. Physical properties of a restorative material, such as polymerisation shrinkage, water sorption, solubility, elastic modulus and shear strength, all have an effect on stress distribution and can significantly affect margin integrity. This review will focus on two aspects of margin deterioration in the oral environment: the in vitro testing of margin seal using emersion techniques to simulate the oral environment and to predict clinical margin failure and the relationship between clinically observable microleakage and secondary caries. The many variables associated with in vitro testing of marginal leakage and the interpretation of the data are presented in detail. The most recent studies of marginal leakage mirror earlier methodology and lack validity and reliability. The lack of standardised testing procedures makes it impossible to compare studies or to predict the clinical performance of adhesive materials. Continual repeated in vitro studies contribute little to the science in this area. Clinical evidence is cited to refute earlier conclusions that clinical microleakage (penetrating margin discoloration) leads to caries development and is an indication for restoration replacement. Margin defects, without visible evidence of soft dentin on the wall or base of the defect, should be monitored, repaired or resealed, in lieu of total restoration replacement.

The effects of three dry-field techniques on intraoral temperature and relative humidity

BACKGROUND

The authors evaluated the effects of three dry-field techniques (rubber dam, Isolite i2 [Isolite Systems, Santa Barbara, Calif.] and Coolex [APT, Osaka, Japan]) on intraoral temperature and relative humidity (RH), compared with the effects of a nonisolated control on intraoral temperature and RH.

METHODS

The authors measured the room's temperature and RH and then placed dry-field devices in five participants' mouths and measured the intraoral temperature and RH for 20 minutes. They then removed the devices or turned off the vacuum system and measured intraoral temperature for an additional five minutes.

RESULTS

The authors found no significant differences in either intraoral temperature or RH at any time during the measurement period in the isolated control group (P > .05); the intraoral temperature was more than 30°C and RH was more than 95 percent. On the other hand, the use of dry-field techniques significantly reduced both intraoral temperature and RH when the rubber dam was in place or the vacuums were turned on (P > .05). The intraoral temperature and RH gradually increased after the authors removed the rubber dam or turned off the vacuums.

CONCLUSIONS

The results of this study revealed that all three dry-field techniques could reduce both temperature and RH effectively.

CLINICAL IMPLICATIONS

Both Isolite i2 and Coolex could provide environments similar to the room conditions used during in vitro specimen preparation for investigating the mechanical properties of dental restorative materials.

Two-year clinical effectiveness of adhesives and retention form on resin composite restorations of non-carious cervical lesions

The current study investigated the clinical effectiveness of three adhesives and the use of retention form in Class V resin composite restorations of the non-carious cervical lesion (NCCL) over a two-year period. One-hundred and fifty NCCLs in 39 patients were restored with resin composites according to six experimental protocols combining the presence or absence of retention form and three adhesives: ScotchBond Multi-Purpose (MP, 3M ESPE), an experimental adhesive (EX, Vericom) and Adper Prompt (AP, 3M ESPE). All restorations were evaluated at baseline, 6, 12 and 24 months. Modified United States Public Health Service (USPHS) criteria were used to evaluate the restorations. MP was found to have significantly superior marginal adaptation than AP in cumulative logistic regression analysis (odds ratio, 2.12; 95% confidence interval, 1.05-4.31; p = 0.0397). In analysis using the Pearson's Chi-square or Fisher's Exact Test to compare the clinical performance of restorations with and without retention form, EX with retention form showed a significantly higher retention rate at two years than that without retention form (p = 0.0089). Restorations with retention form also showed significantly less marginal discoloration than those without retention form in all three adhesives (p = 0.0336).

[Methods of bonding to the enamel in orthodontics]

Mastery of the bonding stage of treatment is clearly a critical step in the clinical practice of orthodontics. There is such a wide variety of products available in orthodontics that a reasoned assessment of bonding systems is a practical necessity. Composite plastics, associated with hydrophobic or hydro-compatible adhesive systems, and the CVIMAR represent the two principal types of bonding agents used in dentistry. They are categorized according to their constituents into a wide range of products whose nuanced differences are sometimes difficult to discern. This paper first focuses on the development of the composition of the various materials, a depiction of the fundamental parameters of adhesion, and a detailed terminology to help the reader reach a basic understanding. Bonding systems are designed to fulfill the requirements of specific clinical situations. A description of their modes of adhesion, of their composition, and of their advantages and disadvantages will be presented in the second part of this article.

Role of Additional Retention on Marginal Adaptation and Sealing of Large Resin Composite Class II Restorations

Retention grooves in proximal box cavities can minimize microleakage and improve marginal adaptation of large resin composite Class II restorations.

Gingival microleakage of Class II resin composite restorations with fiber inserts

PURPOSE

This investigation evaluated the effect of glass and polyethylene fiber inserts on the microleakage of Class II composite restorations with gingival margins on root surfaces.

METHODS

Fifty-four intact molars were sterilized with Gamma irradiation and mounted in acrylic bases. Class II slot cavities were made on both proximal sides of each tooth (3 mm wide, 1.5 mm deep) with the gingival margin on the root surface. The teeth were divided into nine groups, according to the technique of restoration and type of bonding agent. Filtek P-60 (3M/ESPE) was used to restore all cavities. Two types of fiber inserts were used: glass fiber (Ever Stick, StickTech) and polyethylene (Ribbond-THM), with three bonding agents being employed: Scotch Bond Multipurpose (3M/ESPE), Clearfil SE Bond (Kuraray) and Xeno IV (Dentsply). In the experimental groups, 3 mm long fiber inserts were inserted into restorations at the gingival seat. The control groups had no fiber inserts. The restorations were made incrementally and cured with LED light (UltraLume5, Ultradent). The restored teeth were stored in water for two weeks, then thermocycled for 3000 cycles (5 degrees C and 55 degrees C). The tooth surfaces were sealed with nail polish, except at the restoration margins. The teeth were immersed in 2% procion red dye solution, sectioned and dye penetration was assessed to determine the extent of microleakage according to a six-point scale.

RESULTS

The fiber groups generally showed reduced microleakage scores compared to the control groups. The Clearfil SE Bond (Kuraray)/Filtek P-60 (3M/ESPE) combination produced the lowest degree of microleakage, irrespective of fiber type. However, the glass fiber groups were more consistent in reducing microleakage than the polyethylene groups.

CONCLUSIONS

The use of fiber inserts significantly reduced gingival microleakage in Class II composite restorations with gingival margins in dentin, irrespective of the adhesive used. Clearfil SE Bond (Kuraray)/Filtek P60 (3M/ESPE) produced the lowest microleakage scores.

Influence of adhesive systems and flowable composite lining on bond strength of class II restorations submitted to thermal and mechanical stresses

The purpose of this study was to evaluate the effect of adhesive systems and flowable composite lining on bond strength to gingival margins of Class II restorations after thermal/mechanical stresses. Proximal cavities were prepared in 90 bovine incisors. Teeth were assigned into nine groups (n = 10), according to the combination of bonding agent [Single Bond (SB), Optibond Solo Plus (OP), Prime & Bond NT (NT)] and layer (1 mm) of flowable composite Filtek Flow (FF) [absent, one layer, two layers]. Materials were applied according to manufacturers' instructions, and FF layers were photoactivated separately. Restorations were concluded with composite resin and were submitted to thermal (1000x, 5-55 degrees C) and mechanical stresses (100,000x, 80 N). For microtensile evaluation, slabs from the gingival bonded interface were obtained, tested under tension, and their failure mode was observed by scanning electron microscopy. Bond strength data were analyzed using two-way ANOVA/Tukey's test. No interaction was observed between adhesive systems and FF lining (p = 0.89). Also, no significant difference was found between bond strength values, whether or not FF layers were used (p = 0.33). However, bonding systems demonstrated significant differences (p = 0.01). SB and NT presented means higher than those observed with OP. Fracture modes varied considerably between experimental groups, and a greater frequency of cohesive failures was noted when FF layers were used.