Warm Air Delivery in Adhesive Application: Effect on Bonding Performance and Morphological Outcomes

Solvent evaporation within an adhesive layer is a crucial step during a bonding process. The aim of this current research was to test whether the use of different air temperatures (20 °C, 40 °C, and 60 °C) for solvent evaporation improves the performance of four adhesive systems to dentin. Sixty non-carious human molar teeth were randomly prepared for micro-tensile bond strength (μTBS) tests. Four different adhesive systems, Prime&Bond Universal (PBU), OptiBond Universal (OBU), OptiBond FL (OBFL), and Clearfil SE (CSE), were applied following the manufacturer's instructions. Three groups based on the air-drying temperature were used: solvent evaporation was performed with either of warm (40 °C), (60 °C), and cold air as control group (20 °C) for 10 s at a distance of 5 cm. In all bonded surfaces, three resin composite (Reflectys, Itena Clinical, Paris, France) layers of 2 mm thickness were built up. The resin-dentin samples were kept in distilled water at 37 °C for 24 h and 6 months, respectively, before μTBS testing. Failure analysis, scanning electron microscopy of resin-dentin bonded interface, and solvent evaporation rate were tested as secondary variables. All analyses were conducted using a significance level of α = 0.05. Bond strength (BS) values were similar among all the adhesive systems used (p > 0.05). Also, the aging factor did not affect the BS (p > 0.05). Only the factor of temperature used for solvent evaporation resulted in a statistically significant effect (p < 0.05), with the temperature of 60 °C being the highest value (p < 0.05). A failure mode evaluation revealed mostly adhesive or mixed modes of failures in all the different temperatures of air used for the solvent evaporation of each adhesive system. The thickness of the adhesive layer and the creation of resin tags varied amongst the temperatures evaluated. For all adhesive systems tested, the use of 40 °C or 60 °C air for solvent evaporation led to an increased mass loss. Warmer temperatures for solvent evaporation contributed positively to bonding performance, enhancing both the quality of the adhesive layer and its interaction with the dentin tissue. Optimizing solvent evaporation with warmer air temperatures (40 °C and 60 °C) significantly improved µTBS, offering a practical means to enhance the quality and longevity of adhesive restorations in esthetic dentistry.

[Evolution and effectiveness of seventh and eighth generation adhesive systems in direct restorations. a review]

Introduction

: Dental adhesion is responsible for the chemical processes of dentin-enamel union for a correct choice before its application in restorative treatments; it is important to know properly the generation to which it belongs, its properties, application techniques, etc. All this is to ensure success in the procedures to be performed. Currently, adhesive systems have evolved, and 8 generations are available in the market, each with a better-quality standard than the previous one.

Objective

To identify which generation of the adhesive system is the most viable to be applied in direct dental restorative treatments.

Materials and methods

We reviewed and compiled 133 articles published from 20 years ago to date. After analyzing them according to their clinical relevance, 88 were excluded, the remaining articles were reanalyzed, of which only those focused on describing the generations of adhesive systems applied in direct restorations were selected, leaving a total of 56 articles, which included clinical case reports. The Google Scholar search engine, SciELO and databases of interest, such as PubMed, Scopus and Medigraphic, were used, three reviewers independently performed the analysis and search of data, and the keywords were used; adhesive systems, generations of adhesive systems, evolution, and direct restorations.

Results

: 56 articles were evaluated, according to their relationship with the subject and with the information previously sought, it was determined that the seventh generation of adhesive systems is the most viable to be applied in dental treatments, due to the improvements it presents in its characteristics, and the results with good prognosis mentioned by both dental professionals, as in research.

Conclusion

The advancement of technology implies new knowledge; therefore, the effectiveness of adhesive systems has changed significantly. Scientific evidence has shown that seventh-generation adhesives are more effective in direct restorations.

Direct vs indirect restorations for diastema closure: determining the suitable approach

Determining the appropriate technique for diastema closure is challenging, and the decision must be evidence based. The objective of these case reports is to describe different approaches to diastema closure using direct and indirect techniques, focusing on the characteristics of the patient and clinical requirements to guide treatment. In the first case, a 16-year-old patient had multiple diastemas in the maxillary anterior dentition. The clinical evaluation revealed microdontia of the lateral incisors and malpositioned teeth. The treatment included tooth whitening and placement of composite resin veneers using a direct technique. In the second case, a 54-year-old patient displayed a disharmonious and esthetically compromised smile due to small teeth, color changes, multiple diastemas, incisal wear, and severe dentogingival disproportion. Based on the patient's expectations, the patient's age, and the presence of a "black triangle" interdental space, a multidisciplinary restorative treatment was proposed, including gingivoplasty, tooth whitening, and placement of ceramic laminate veneers using an indirect technique. Both approaches achieved successful esthetic rehabilitation and diastema closure with minimal intervention. The choice of procedure and restorative material, as well as the need for tooth preparation, varied based on the clinical requirements, patient expectations, and financial constraints. Careful treatment planning avoided lengthy and inefficient procedures.

Shade matching and blending capabilities of a new single-shade composite: an in vivo study

Demand for direct esthetic restorations is high, but shade matching can be challenging. Some manufacturers claim that a single product is able to match all colors of the human dentition, eliminating shade matching challenges. This in vivo study, which followed the International Commission on Illumination's (CIE) CIEDE2000 color difference standard (ΔE00), aimed to quantify the shade matching and blending capabilities of a single-shade composite (Omnichroma PLT) used as a direct veneer. A color difference of ΔE00 ≤ 1.8 was set as the acceptability threshold. Ten participants with an unrestored and noncarious maxillary left central incisor were enrolled in the study. Direct spectrophotometric measurements (CIE L*a*b*) were made on the tooth and then on composite cured on the tooth. Consistency in measurements and composite resin placement were attained through the use of a specially designed jig. A digital photograph was then taken with the composite in place, and colorimetric software was used to obtain the L*a*b* values at the most incisal and cervical edges of the restoration. These values were compared to those of the natural tooth structure immediately adjacent to the composite resin. The ΔE00 scores were calculated to determine the composite's ability to match the tooth shade beneath it (ΔEm) and to blend with the incisal (ΔEi) and cervical (ΔEc) tooth shades. Mean scores for ΔEm, ΔEi, and ΔEc were calculated, and an independent t test (α = 0.05) was used to compare means for ΔEi and ΔEc. The mean (SD) ΔE00 values were 6.16 (2.38), 3.90 (2.47), and 6.84 (1.80) for ΔEm, ΔEi, and ΔEc, respectively. A statistically significant difference (P = 0.008) was observed between ΔEi and ΔEc. As a direct veneer, the tested composite did not meet the acceptability threshold for any ΔE00 measurement; however, it was better at matching the incisal third of the tooth than it was the other thirds. More in vivo studies are needed to verify and expand on these results.

Evaluation of Abfraction Lesions Restored with Three Dental Materials: A Comparative Study

BACKGROUND

Abfraction lesions are manifested as damage to hard tissues in the cervical area of dental crowns. The study aimed to assess the direct restoration of abfraction lesions according to the modified United States Public Health Service (USPHS) criteria for 24 months. The restorations were accomplished with Fuji Bulk-GC, Omnichroma Flow-Tokuyama, and Beautifil® II-Shofu dental materials, and the therapy was or was not associated with wearing thermoformed mouthguards.

METHODS

From the 53 selected and analyzed patients (n = 53), 28 patients (with restorations of abfraction lesions) belonged to the 1st group and 25 patients (with 105 restorations, who also wore mouthguards) belonged to the 2nd group. Blind determination assessments were effectuated at baseline and after 2, 6, 12, 18, and 24 months. Results showed that, regardless of the rating score, there are no significant statistical differences in the evaluation criteria between the two groups of patients Conclusions: For each material, the scores of USPHS criterion presented good clinical performances after 24 months, with no significant statistical differences between the fillings and the applied therapy in the two groups of patients.

Effect of Bleaching Agents on Discoloured Resin-Based Composites for Direct Restorations: A Systematic Review

The purpose of the review was to assess the influence of office and home bleaching on the color durability after staining of resin-based composites (RCs) for direct restorations. A web-based search for possibly relevant scientific papers in the English language between January 2013 and August 2022 was conducted in the databases such as PubMed, Scopus, Cochrane Library, and EMBASE. In-vitro studies that explored the influence of in-office and other bleaching treatments on the discolored RC for direct restorations in extracted human teeth were included. Case studies, case series, animal studies, systematic reviews, and letters to the editor were not considered. A total of 212 articles from a web-based search and 32 studies from a manual search were retrieved. After removal of duplicate records, 181 titles and abstracts were reviewed for eligibility; 92 were chosen for full-text analysis, and nine in-vitro studies matched the inclusion criteria. The two examiners examined the methodological quality of the selected studies independently based on the study design, methodological soundness, and data analysis. Distinct values were assigned to studies evaluating color variations of stained RC subjected to bleaching agents. The methodological quality scores were expressed as a percentage of the highest possible score based on the established scoring system and categorized as indicating a low, moderate, and high level of evidence. The reversal of color alterations following home and office bleaching was found to be dependent on the RC used. Within the limitations of the in-vitro investigations, it was deduced that the bleaching agents were successful in eliminating stains and improving the durability of the color to near baseline values.

Longevity of Indirect and Direct Restorations in Anterior Teeth

It is the aim of this paper to present data on the survival of direct and indirect restorations in anterior teeth. Two sources of information are used: previously-published analysis of data from 1990 to 2006 from a 13 million restoration dataset from England and Wales; and evidence from published literature from 2011 to the time of writing (March 2022). The findings suggest that: (1) directly-placed resin composite materials may provide satisfactory survival of restorations in anterior teeth; (2) crowns provide better survival to re-intervention: however, crowning an incisor or canine tooth, as opposed to placement of a direct restoration, will lead to an earlier time to extraction of the restored tooth; (3) veneers perform more favourably than other restorations in terms of time to extraction of the restored tooth, but may have a less favourable time to re-intervention than crowns; (4) lithium disilicate crowns may be considered to perform satisfactorily with regard to time to re-intervention when placed in anterior teeth, but less satisfactorily in posterior teeth; and (5) operator factors influence survival of restorations.

Effects of nanohybrid, flowable, resin-based composites on fibroblast viability using different light-curing units

PURPOSE

To investigate the in vitro cytotoxic effects of Bis-GMA-containing and Bis-GMA-free flowable resin-based composites (RBCs) on primary human gingival fibroblast cells (hGFc) using direct and indirect curing methods and three different light-curing units (LCUs) MATERIALS AND METHODS: Cells were isolated and cultured in vitro in 24-well plates. The plates were divided into treatment (cells with RBC), control (cells only), and blank (media only) groups. In the treatment groups, two types of nanohybrid flowable RBCs were used: Bis-GMA-free and Bis-GMA groups. Each treatment group was subdivided according to the curing method, i.e., direct curing (RBC was injected into the wells and cured directly on the attached cells) and indirect curing (the samples were pre-cured outside of the well plate and then added to the well plate with cells). To vary the LCU, the subgroups were further divided into three groups: multiple-emission peak light-emitting diode, single-emission peak light-emitting diode, and quartz-tungsten-halogen units. Curing was conducted for 20 s. The hGFc cytotoxicity was evaluated via 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay after 24, 48, and 72 h of culturing RESULTS: The MTT assay results showed that both RBCs were significantly cytotoxic toward hGFc compared to the control group (p < 0.0001). The Bis-GMA group was significantly more cytotoxic to the cells compared to the Bis-GMA-free group. In addition, the curing method and time interval affected cell viability regardless of the LCU used CONCLUSION: The Bis-GMA flowable RBC and direct curing method had the highest cytotoxic effects on hGFc regardless of the LCU used. Careful selection of flowable RBCs and proper curing techniques are required to decrease the cytotoxic effects on hGFc and improve the clinical handling of oral tissues. This article is protected by copyright. All rights reserved.

Color stability of resin-based composites: Staining procedures with liquids-A narrative review

OBJECTIVE

The objective of this study was to review the experimental staining procedures performed in in-vitro studies for evaluating color stability of resin-based composites used for direct restorations.

OVERVIEW

A review was performed with the purpose to identify in vitro procedures carried out to establish staining and color stability of resin-based composites used for direct restorations. A literature search was performed on four online databases (PubMed, Scopus, Embase and Web of Science) for articles published from January 1st 2001 till March 20th 2021, using a combination of free words and Medical Subject Headings (MESH) terms: "Composite Resins" AND "Color Stability" OR "Staining." Two reviewers screened titles and/or abstracts of 1728 unique studies. In total, 208 studies were selected for full-text reading, from which 178 were included in the review. The assessed variables were specimen dimensions, shape, and surface finishing; time before immersion; staining media type, dwell time, temperature and renewal interval; type of composite; color and translucency assessment parameters and measuring system. One hundred and seventy-eight articles analyzed color stability with staining liquids. Coffee was the most used staining medium (n = 102), followed by tea (n = 61), and red wine (n = 55). A disc-shaped specimen was used in most studies (n = 170) with a 2 mm thickness (n = 116). Spectrophotometers were the most used color assessment devices (n = 154), followed by colorimeters (n = 17). Color differences were quantified with ΔE (n = 154), ΔE00 (n = 23). Acceptability and or perceptibility thresholds were also taken into consideration (n = 126).

CONCLUSIONS

The large variety of staining procedure suggests the need for standardization.

CLINICAL SIGNIFICANCE

Aesthetic failure due to discoloration is a relevant clinical problem. Evaluating benefits and drawbacks of resin based composites artificial staining procedures will improve to predict materials clinical performances.

One-Year Clinical Performance of Activa™ Bioactive-Restorative Composite in Primary Molars

Restorative procedures for caries affecting primary molars are a daily challenge for pediatric dentistry, and one of the main factors influencing the results of these restorative procedures is the choice of dental material used: bioactive materials were recently introduced, combining the strength of composites and the benefits of glass ionomers. The present study’s objective is to clinically evaluate the aesthetic, functional and biological properties of Activa™ Bioactive composite in approximal and occlusal carious lesions for 1 year using the FDI criteria for evaluating direct dental restorations. Forty-five children with occlusal or approximal caries in first or second primary molars were included in the study: the cavities were then randomized to be restored with either Activa BioActive or SDR Bulk-fill and evaluated over time according to Federation Dentaire Internationale (FDI) criteria. Results showed that Activa BioActive composite has similar performance over time compared to Bulk-fill composite, for both functional and aesthetic properties. Thus, within the limitations of this study, including the short follow-up period, it can be concluded that bioactive materials might be the material of choice to restore primary molars. A longer follow-up period is desirable to confirm these findings.

Direct and Indirect Restorations for Endodontically Treated Teeth: A Systematic Review and Meta-analysis, IAAD 2017 Consensus Conference Paper

PURPOSE

The primary objective of this systematic review was to compare treatment outcomes of direct and indirect permanent restorations in endodontically treated teeth, and provide clinical suggestions for restoring teeth after endodontic treatment.

MATERIALS AND METHODS

Electronic databases (Medline, EMBASE, CENTRAL) and gray literature were screened for articles in English that reported on prospective and retrospective clinical studies of direct or indirect restorations after endodontic treatment with an observation period of at least 3 years. Primary outcomes were determined to be short-term (≤ 5 years) and medium-term (> 5 and ≤ 10 years) survival. Secondary outcomes included restorative and endodontic success of restored teeth. The quality of included studies and risk of bias were assessed using Cochrane Collaboration's tool for RCTs (randomized controlled trials), the Newcastle-Ottawa Scale for cohort studies, and the Agency for Healthcare Research and Quality (AHRQ) methodology checklist for cross-sectional studies. The GRADE system was used for assessing collective strength of the overall body of evidence.

RESULTS

Of 2547 screened articles, only 9 (2 RCTs, 3 retrospective cohort studies, 3 cross-sectional studies) met the inclusion criteria, and 8 studies were used in the meta-analysis. In general, indirect restorations (mostly full crowns) showed higher 5-year survival (OR 0.28, 95% CI 0.19-0.43, p < 0.00001) and 10-year survival (OR 0.20, 95% CI 0.12-0.31, p < 0.00001) than direct restorations. However, there was no statistical difference in short-term (≤ 5-years) restorative success (OR 0.32, 95% CI 0.05-2.12, p = 0.24) and endodontic success (OR 0.88, 95% CI 0.72-1.08, p = 0.22).

CONCLUSIONS

Based on current evidence, there is a weak recommendation for indirect restorations to restore endodontically treated teeth, especially for teeth with extensive coronal damage. Indirect restorations using mostly crowns have higher short-term (5-year) and medium-term (10-year) survival than do direct restorations using composite or amalgam (GRADE quality of evidence: low to moderate), but no difference in short-term (≤ 5 years) restorative success (low quality) and endodontic success (very low quality). There is a need for high-quality clinical trials, especially well-designed RCTs.

Failure of single-unit restorations on root filled posterior teeth: a systematic review

This systematic review investigated the failure rate of conventional single-unit restorations in root filled posterior permanent teeth. Two reviewers independently applied eligibility criteria, extracted data and assessed the quality of the evidence of each included study according to the Cochrane Collaboration's procedures for randomized control trials (RCTs) and the STROBE criteria for observational studies. The MEDLINE (via Ovid), EMBASE (via Ovid), Cochrane Oral Health Group Trials Register and CENTRAL (via Cochrane Library) databases were searched electronically (January 1993 to week 1, February 2015). This was complemented by an additional hand search of selected journals and the references of relevant studies. Clinical studies published on root filled single-unit restorative treatments with a mean follow-up period of at least 3 years were selected. The outcome measured was clinical or radiological failure. Overall, the four RCTs and the single observational study included were of low and high quality, respectively. Therefore, a meta-analysis was not possible. The pooled mean failure rates were reported according to the type of treatment and remaining coronal tooth structure. The current evidence suggested that the failure rates of the treatments may depend on the amount of remaining tooth structure and type of treatment. Post-retained crowns were associated with the most favourable outcome in teeth with one to two remaining coronal tooth wall(s), whereas post-free crowns were superior when greater tooth structure was available. Restorations in teeth without ferrules had such a high rate of failure that other treatment options should be considered.

Factors affecting the placement or replacement of direct restorations in a dental school

Context:

The knowledge of the reasons for the placement of direct restorations makes possible to trace an epidemiological profile of a specific population and to direct the teaching of dentistry to techniques that are commonly used today and will be continued performed in the future.

Purpose:

The aim of this study was to verify the reasons for placement and replacement of direct restorations in patients treated in the Dental Clinic of the Uberaba University – Brazil.

Materials and Methods:

This study evaluated 306 restorative procedures carried out on 60 patients. During the treatment planning, a form that contained information about the patient's gender, tooth number, the classification of restorations, the reasons for placement and replacement of amalgam and tooth-colored restorations, the material that had to be removed and the new material used to fill the cavities was filled for each patient. Statistical analysis was carried out using Chi-square test (α = 0.05).

Results:

The data showed that most of the patients were female (66.7%). Of all the restorations placed, 60.45% were 1^st-time placements, while 39.55% were replacements. For 1^st-time restorations, the main reason for placement was primary caries (76.76%), followed by non-carious cervical lesions (15.14%). The amalgam restorations were replaced more frequently (67.77%). The primary reason for replacements was the presence of secondary caries (for both previous amalgam (42.68%) and composite (66.67%) restorations (P < 0.05). The resin composite was the most indicated material for the new restorations (98.04%) (P < 0.05).

Conclusions:

The main reason for placement of direct restorations was primary caries, while secondary caries was the main reason for replacements. In almost all cases, the material used to fill the cavities was the resin composite.

Evaluation of bond strength of different adhesive systems: Shear and Microtensile Bond Strength Test

OBJECTIVES

Aim of this work is the in vitro bond strength evaluation of three bonding agents comparing the results of two kinds of test, Microtensile Bond Strength Test and a Shear Bond Strength Test. Bond strength tests have been used to test both direct and indirect restorative techniques to investigate if methods could give different results.

METHODS

72 human third molars have been collected and stored in physiological solution. Three kinds of test were conducted: 1- SB, 2- "Slice" preparation μTBS1, 3- "Stick" preparation μTBS2. We tested three different adhesive systems (Groups 1-2-3 n=24), two restorative techniques (subgroup A-B n=12). The tested adhesives were: Optibond FL (OFL) (Group 1), Optibond Solo Plus (OSP) (Group 2), Optibond Solo Plus Self-Etch (OSSE) (Group 3). For all tests was used a universal load machine Instron Machine.

RESULTS

Best values were found for Optibond FL with mean values of 45-50 MPa. Optibond Solo Plus resulted in values very similar and in some cases almost identical to FL. Optibond Solo Self Etch showed poorer adhesion in both direct and indirect restorative techniques. The parametric and non parametric statistical variance analysis pointed out the absence of significant differences between OFL and OSP, and demonstrated a significant difference for OSSE adhesive.

SIGNIFICANCE

The results confirm that a total etch two-step adhesive is the best compromise between easiness and effectiveness.