Adaptation and radiographic evaluation of four adhesive systems

Evaluation of Newly Introduced Bioactive Materials in Terms of Cavity Floor Adaptation: OCT Study

OBJECTIVE

The aim of the present study was to evaluate the adaptation of newly introduced bioactive restorative materials to the cavity floor using cross-polarization optical coherence tomography (CP-OCT).

MATERIALS AND METHODS

Round class V cavities were prepared on the proximal surfaces of sixty non-carious human anterior teeth (0.5 mm depth × 4 mm diameter), which were divided into groups according to the restorative material (n = 15). In the VF group, Vertise flow composite (Kerr, Orange, CA, USA) was used, in the BF group, Beautifil II composite (Shofu, Koyoto, Japan) was used, and in the AB group, ACTIVA BioACTIVE composite (Pulpdent, Watertown, NY, USA) was used. Cavities were restored using the bulk filling technique and cured according to the manufacturers' instructions. Then, the specimens were immersed in a contrasting agent, and image acquisitions were taken by CP-OCT to calculate the adaptation percentage by using an image analysis software.

RESULTS

B-scans showed a diffuse bright band of white pixels at the tooth-resin interface that was interpreted as a micro-gap present between the cavity floor and restorative material. The Kruskal-Wallis test showed a statistically significant difference between all tested groups with the AB group representing the least gap formation, followed by the BF group, and then the VF group, which demonstrated the highest gap formation.

CONCLUSIONS

In class V cavities, better adaptation to the cavity floor can be obtained when using ACTIVA BioACTIVE more than Vertise flow and Beautifil II composites. In addition, CP-OCT is considered a non-destructive imaging tool that helps in evaluating the quality of the tooth-restoration interface when bioactive composites are used.

Wave Frequency Effects on Damage Imaging in Adhesive Joints Using Lamb Waves and RMS

Structural adhesive joints have numerous applications in many fields of industry. The gradual deterioration of adhesive material over time causes a possibility of unexpected failure and the need for non-destructive testing of existing joints. The Lamb wave propagation method is one of the most promising techniques for the damage identification of such connections. The aim of this study was experimental and numerical research on the effects of the wave frequency on damage identification in a single-lap adhesive joint of steel plates. The ultrasonic waves were excited at one point of an analyzed specimen and then measured in a certain area of the joint. The recorded wave velocity signals were processed by the way of a root mean square (RMS) calculation, giving the actual position and geometry of defects. In addition to the visual assessment of damage maps, a statistical analysis was conducted. The influence of an excitation frequency value on the obtained visualizations was considered experimentally and numerically in the wide range for a single defect. Supplementary finite element method (FEM) calculations were performed for three additional damage variants. The results revealed some limitations of the proposed method. The main conclusion was that the effectiveness of measurements strongly depends on the chosen wave frequency value.

Adaptation Assessment of Three Bonded Resin Restorations at the Cavity Floor Using Cross-Polarization Optical Coherence Tomography

Objective: The aim of the study was to compare the composite adaptation of three systems by using cross-polarization optical coherence tomography (CP-OCT). Background data: Most polymer-based restorations suffer from polymerization shrinkage that affects the interfacial seal. This shrinkage cannot be detected by conventional X-ray methods. Optical coherence tomography was proved to be a reliable non-invasive imaging tool to examine biological structures and biomaterials at micron scale. Methods: Twenty-four cylindrical class-V cavities were prepared on the buccal surfaces of the extracted human molars. After cavity preparation, samples were randomly divided into three groups (n = 8) according to the restoration system: one-step self-etch Clearfil Tri-S Bond Plus with Clearfil Majesty ES-2 composite (TS; Kuraray Noritake Dental), Single Bond Universal in self-etch mode with Filtek Z350 XT composite (SB; 3M ESPE), and one-step self-etch Plafique Bond with Plafique LX 5 composite (PB; Tokuyama Dental). The restoration placement was carried out according to the manufacturers' recommendations. Later, the specimens were immersed in a contrasting agent; then, image acquisitions were taken by CP-OCT to calculate the adaptation percentage by using an image analysis software. Results: Mann-Whitney U test showed no statistical significant difference in the adaptation percentage between TS (91.72 ± 11.6) and SB (93.43 ± 6.9) groups (p > 0.05). However, the adaptation percentage in PB (41.83 ± 28.5) was significantly lower than in the other tested groups (p < 0.05). Conclusions: Within the limitation of the study, TS and SB groups showed better adaptation than PB. Moreover, CP-OCT is a useful imaging tool that can display composite adaptation at micron scale.

Evaluating ceramic crown margins with digital radiography

STATEMENT OF PROBLEM

Radiographs aid in clinically determining crown fit, specifically interproximal margins where tactile and visual methods may be limited. However, investigations of the utility of digital radiographs as a tool for evaluating the marginal openings of ceramic crowns are lacking.

PURPOSE

The purpose of this in vitro study was to assess whether marginal adaptation for ceramic crowns and for metal-ceramic crowns with a metal collar can be identified with digital radiographs.

MATERIAL AND METHODS

One lithium disilicate crown, 1 fluorapatite crown, and 1 metal-ceramic crown were fabricated for a maxillary premolar. The crowns were attached to a custom-designed device that allowed the marginal discrepancy to be changed. A total of 10 increments were measured starting at 0 to 20 μm and increasing every 20 μm to a maximum opening of 180 to 200 μm. At each increment, 2 radiographs were made of the crowns, using a digital sensor, 1 perpendicular to and 1 at 80 degrees to the long axis of the tooth. To test whether digital radiographs could be used to accurately identify "acceptable" and "unacceptable" margins, 21 dentists were asked to rate the radiographs as "acceptable" or "unacceptable." The chi square test was used to analyze differences between the dentists' evaluations and the actual marginal opening (α=.05). For the purposes of this study, a marginal discrepancy greater than 80 μm was considered "unacceptable."

RESULTS

Of all marginal discrepancies exceeding 80 μm, 78.6% of the metal-ceramic crown radiographs were incorrectly scored as "acceptable" (P<.001). These radiographs were identified as false positives. Lithium disilicate (66.1%) and fluorapatite (45.8%) crowns were more likely to be incorrectly evaluated as "unacceptable" (P<.001) and identified as false negatives.

CONCLUSIONS

Using digital radiographs to evaluate marginal adaptation without clinical examination is not by itself an accurate method of evaluating the marginal fit of complete coverage crowns. The marginal fit of the tested metal-ceramic crowns tended to be evaluated incorrectly as acceptable. The marginal fit of the tested ceramic crowns tended to be evaluated incorrectly as unacceptable.

Comparison of microleakage of Scotchbond™ Universal Adhesive with methacrylate resin in Class V restorations by two methods: Swept source optical coherence tomography and dye penetration

Background:

One of the most important factors in restoration failure is microleakage at the restoration interface. Furthermore, a new generation of bonding, Scotchbond Universal (multi-mode adhesive), has been introduced to facilitate the bonding steps. The aim of this study was to compare the microleakage of Class V cavities restored using Scotchbond™ Universal with Scotchbond Multi-Purpose in two procedures.

Materials and Methods:

Eighteen freshly extracted human molars were used in this study. Thirty-six standardized Class V cavities were prepared on the buccal and lingual surfaces. The teeth were divided into three groups: (1) Group A: Scotchbond Universal with “self-etching” procedure and nanohybrid composite Filtek Z350. (2) Group B: Scotchbond Universal with “total etching” procedure and Filtek Z350. (3) Group C: Scotchbond Multi-Purpose and Filtek Z350. Microleakage at enamel and dentinal margins was evaluated after thermocycling under 5000 cycles by two methods of microleakage assay: swept source optical coherence tomography (OCT) and dye penetration. Wilcoxon's signed-rank test and Kruskal–Wallis test were used to analyze microleakage.

Results:

In silver nitrate dye penetration method, group A exhibited the minimum microleakage at dentin margins and group C exhibited the minimum microleakage at enamel margins (P < 0.05). Furthermore, in OCT method, group C demonstrated the minimum microleakage at enamel margins (P = 0.047), with no difference in the microleakage rate at dentin margins.

Conclusion:

Scotchbond Universal with “self-etching” procedure at dentin margin exhibited more acceptable performance compared to the Scotchbond Multi-Purpose with the two methods.

The Thickness of the Adhesive Layer Increases the Misdiagnosing of the Radiolucent Zones and Restoration Replacement Indication

OBJECTIVE

To evaluate the influence of the thickness of the adhesive layer and demineralized dentin on the decision to replace composite restoration.

MATERIALS AND METHODS

Eighty human third molars with occlusal preparations (Class I) were randomly assigned to eight groups (n = 10): adhesive system (Clearfil SE Bond [CSE] or Scotchbond Universal Adhesive [SBU]); the number of adhesive layers (one or two); and substrate (sound or demineralized dentin). A blinded examiner evaluated radiographs of each restored tooth. Obtained scores for the presence or absence of radiolucent zone under restoration were submitted to a relative risk (RR) calculus and Z-test, and the scores for the decision to replace restorations were submitted to Fisher's exact test (p < 0.05).

RESULTS

The relative risk of identifying a radiolucent zone under restoration in sound and demineralized dentin were, respectively, 2 and 1.85 times higher when two layers of adhesive were applied. Demineralized dentin did not increase the probability of identifying a radiolucent zone. A higher relative (1.6, p = 0.01) was observed when two layers of SBU were applied. The number of layers did not influence the relative risk for CSE (RR = 1.3, p = 0.13).

CONCLUSION

Thicker layers of SBU increase the relative risk of identifying a radiolucent layer under restoration and the decision to replace a/composite restoration, irrespective of the substrate. The presence of demineralized dentin did not increase the probability of identifying a radiolucent zone when compared to sound dentin.

CLINICAL SIGNIFICANCE

The results of this in vitro study suggest that thicker layers of a particular adhesive under resin composite restorations can negatively influence the decision to replace them. (J Esthet Restor Dent 29:193-200, 2017).

Application of Optical Coherence Tomography (OCT) for Diagnosis of Caries, Cracks, and Defects of Restorations

Optical coherence tomography (OCT) is a noninvasive technique providing cross-sectional images of a tooth structure. This review describes the use of OCT for detecting dental caries, tooth fractures, and interfacial gaps in intraoral restorations. OCT can be a reliable and an accurate method and a safer alternative to X-ray radiography.

The influence of bonding agents on the decision to replace composite restorations

This in vitro study evaluated the validity of the decision to replace of a restoration based upon the radiolucent zone beneath a resin composite.

MATERIALS AND METHODS

Class II cavities were prepared on the approximal surfaces of 40 molars. The teeth were divided into four groups. Clearfil SE Bond, PQ1 or Single Bond was applied in the experimental groups. No bonding agent was used in the control group. Following the restorations, digital radiographs were obtained and independently evaluated by two oral radiologists and two specialists in restorative dentistry to determine the need for replacement. The coronal portions of the teeth were then sectioned and the interfaces between the restorations and cavity walls were examined using an optical light microscope. Possible adhesive pooling and voids were examined under a light microscope. Inter-examiner reliability was evaluated with the Cohen's kappa (kappa) test. Sensitivity, specificity and negative and positive predictive values were calculated. Kruskal-Wallis, followed by the Mann-Whitney U-test, determined differences among the pooling thicknesses of the different adhesives.

RESULTS

Various sensitivity and specificity degrees were obtained from the groups in which different adhesive systems were used. The PQ1 adhesive system was the best for identifying well-adapted restorations with the highest true non-replacement diagnosis (TND = 0.70). Clearfil SE Bond had the highest false positive scores. Adhesive pooling was significantly different in the experimental groups of the current study (p < 0.05).

CONCLUSION

Replacement decisions for a resin composite restoration based upon digital images frequently resulted in false-positive or negative decisions.

Effect of two-step adhesive systems on inhibition of secondary caries around fluoride-releasing resin composite restorations in root dentine

OBJECTIVE

The purpose of this study was to investigate the effect of two-step adhesive systems on secondary caries inhibition around fluoride-releasing materials in vitro.

METHODS

Two self-etching primer systems, Clearfil SE Bond (SE) and UniFil Bond (UB), and two one-bottle systems with a total-etch wet-bonding technique, Single Bond (SB) and One-Step (OS), were used prior to placement of resin composites either with (Reactmer) or without (Z100) fluoride release. Class V cavities prepared in extracted human premolars were restored with various combinations of materials: Reactmer/SE, Reactmer/UB, Reactmer/SB, Reactmer/OS, Z100/SE, Z100/UB, Z100/SB and Z100/OS. After storage for 14 days, the restored teeth were incubated in bacterial medium containing sucrose with Streptoccus mutans for 2 weeks. Water sorption and desorption of the adhesives and fluoride release from the resins either coated with adhesive or uncoated were also determined.

RESULTS

The one-bottle groups showed higher water sorption and desorption than the self-etching primer groups. Although fluoride release from the Reactmer specimens was suppressed by the adhesive coating, the one-bottle groups allowed significantly higher fluoride release than the self-etching primer groups. On microradiographs, the radio-opaque layers adjacent to the Reactmer restorations were thick and clear, while the layers adjacent to the Z100 restorations were thin and unclear. For the Reactmer restorations, the radio-opaque layers associated with the one-bottle groups were significantly thicker than for the self-etching primer groups.

CONCLUSIONS

These results indicated that the use of one-bottle wet-bonding systems for bonding of fluoride-releasing resin composites to dentine may contribute to inhibit secondary caries compared to self-etching primer systems.

Bonding characteristics of self-etching adhesives to intact versus prepared enamel

PURPOSE

This study tested the null hypothesis that the preparation of the enamel surface would not affect the enamel microtensile bond strengths of self-etching adhesive materials.

MATERIALS AND METHODS

Ten bovine incisors were trimmed with a diamond saw to obtain a squared enamel surface with an area of 8 x 8 mm. The specimens were randomly assigned to five adhesives: (1) ABF (Kuraray), an experimental two-bottle self-etching adhesive; (2) Clearfil SE Bond (Kuraray), a two-bottle self-etching adhesive; (3) One-Up Bond F (Tokuyama), an all-in-one adhesive; (4) Prompt L-Pop (3M ESPE), an all-in-one adhesive; and (5) Single Bond (3M ESPE), a two-bottle total-etch adhesive used as positive control. For each specimen, one half was roughened with a diamond bur for 5 seconds under water spray, whereas the other half was left unprepared. The adhesives were applied as per manufacturers' directions. A universal hybrid composite resin (Filtek Z250, 3M ESPE) was inserted in three layers of 1.5 mm each and light-cured. Specimens were sectioned in X and Y directions to obtain bonded sticks with a cross-sectional area of 0.8 +/- 0.2 mm2. Sticks were tested in tension in an Instron at a cross-speed of 1 mm per minute. Statistical analysis was carried out with two-way analysis of variance and Duncan's test at p < .05. Ten extra specimens were processed for observation under a field-emission scanning electron microscope.

RESULTS

Single Bond, the total-etch adhesive, resulted in statistically higher microtensile bond strength than any of the other adhesives regardless of the enamel preparation (unprepared = 31.5 MPa; prepared = 34.9 MPa, not statistically different at p < .05). All the self-etching adhesives resulted in higher microtensile bond strength when enamel was roughened than when enamel was left unprepared. However, for ABF and for Clearfil SE Bond this difference was not statistically significant at p > .05. When applied to ground enamel, mean bond strengths of Prompt L-Pop were not statistically different from those of Clearfil SE Bond and ABF. One-Up Bond F did not bond to unprepared enamel. Commercial self-etching adhesives performed better on prepared enamel than on unprepared enamel. The field-emission scanning electron microscope revealed a deep interprismatic etching pattern for the total-etch adhesive, whereas the self-etching systems resulted in an etching pattern ranging from absent to moderate.

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

OBJECTIVES

The aim of this in vitro study was to evaluate the influence of a simulation of intra-oral conditions on the microleakage of two adhesive systems (Scotchbond MultiPurpose Plus=SBMP+ and Clearfil SE Bond=SE Bond). For SBMP+, the influence of bonding procedure (comparison between manufacturer's protocol and an experimental procedure) was also studied.

METHODS

Sixty Class II cavities with cervical margins 1mm below the cemento-enamel junction were prepared in the mesial/distal surfaces of recently extracted human molars. For the 3 groups (n=10), the adhesive system was applied under ambient conditions (20 degrees C/40% of relative humidity (RH)) for the mesial cavity and under extreme conditions (35 degrees C/95% RH) for the distal cavity. SBMP+ and SE Bond were applied strictly according to manufacturer's instructions. SBMP+ was also used according to an experimental procedure (intensive evaporation of the primer solvent). Cavities were restored with Z 100. After polishing, the specimens were thermocycled (2000 cycles, 5-55 degrees C). Teeth were coated with nail varnish, immersed in silver nitrate and sectioned longitudinally. The extent of microleakage was measured in percentage of dye penetration. Statistical analysis was performed using a 2 way ANOVA and a Fischer's PLSD test.

RESULTS

Microleakage was dependent on the environmental conditions. In '35 degrees C/95% RH' conditions, dye penetration significantly increased for the 3 groups. For SE Bond, the microleakage percentages were the lowest, both in ambient and extreme conditions. For SBMP+, the experimental procedure allowed a decrease in microleakage, but only in ambient conditions.

CONCLUSIONS

The simulation of intra-oral conditions caused a large increase in microleakage in the 3 groups tested. The self-etching primer presented the best behavior towards the 'temperature/RH' parameters simulated in this study.

Microleakage of composite resins in cavities of upper primary molars

OBJECTIVE

To improve the quality of resin restorations, studies are necessary not only of the physical properties of materials but also of the cavity geometry. We have evaluated marginal microleakage for two types of photo-curing composite resin applied to cavities with different marginal structures.

SAMPLE AND METHODS

The test materials were 91 extracted upper primary molars. The two composite resins used in this experiment were Liner Bond II (LBII) and Photo Clearfil A (PCA). A class I cavity was created in each tooth; the cavity configuration was a round bevel, a straight bevel and a butt joint. The tooth was then restored with each composite resin. Each tooth was exposed to thermal cycles, followed by immersion in 0.2% basic fuchsin solution. Three sections, through the mesial, central and distal areas of each tooth were taken. The penetration of the dye was examined with a stereoscopic microscope. The sites of observation for examination of microleakage were awarded scores of between 0 and 7.

RESULTS

LBII-among the three marginal forms, absence of leakage was observed most frequently in the straight bevel group followed by the round bevel and the butt joint groups, in the mesial and distal sections. In the central section, the straight bevel did not show any scores of 0, 6 or 7. PCA-an absence of leakage in the mesial section occurred most frequently for the round bevel group. However, the absence of leakage in the central and distal sections was most frequent for the straight bevel group. Microleakage of the central section (with scores from 1 to 7) was frequently lower than that for the mesial and distal sections. Scores of 5 and above in the central section were observed only in the butt joint group. The frequency and mean score of leakage were clearly higher in LBII than in PCA, with one significant exception. For both composite resins, the butt joint group showed higher-mean scores of leakage than did either the round or straight bevel group, but for PCA, the mean score of the central section was lower than the other two sections in all groups.

CONCLUSION

Our study shows that beveling does reduce marginal leakage. This leakage was more frequently observed with the use of LBII than with PCA. However, the amount of tooth ground away was greater for the bevel-treated cavity. In considering these features, special care is necessary in selecting the bur for treating a bevelled cavity.

Marginal integrity and postoperative sensitivity in Class 2 resin composite restorations in vivo

INTRODUCTION

Problems that may arise in resin composite Class 2 restorations include microleakage and postoperative sensitivity. However, limited in-vivo research is conducted to evaluate these processes.

AIM

The aim of this study was to assess postoperative sensitivity, microleakage and the pooling of adhesives in relation to Class 2 box-type composite restorations placed in vivo using various adhesive systems and application techniques.

MATERIALS AND METHODS

One hundred and forty-four Class 2 box restorations were placed in the mesial and distal surfaces of 72 premolar teeth in-vivo using one of three combinations of adhesive systems and three filling techniques. After 6 weeks of clinical service postoperative sensitivity was recorded. The teeth were then extracted, immersed in a dye solution and sectioned. Microleakage and pooling of the adhesive was recorded. Statistical analysis involved logistic regression and chi2 tests to identify differences between groups at p < 0.05.

RESULTS

Of the 144 restorations, 65 showed minimal cervical leakage in enamel, 5 suffered leakage into dentin and 74 were free of microleakage. No statistically significant differences were found in cervical microleakage between the adhesive systems or between filling procedures. Occlusal microleakage in the enamel was present in 16 of the 160 restorations. Liner Bond 2 restorations leaked significantly more at the occlusal surface (p < 0.05). Pooling of the adhesive was significantly less when PhotoBond was used. No spontaneous postoperative sensitivity was reported. Twenty-eight restorations were sensitive to loading. Postoperative sensitivity was significantly less in patients with Liner Bond 2 restorations.

CONCLUSIONS

The adhesive systems used in this study showed minimal leakage into dentin in vivo. Using Liner Bond 2, restorations exhibited more occlusal leakage but were significantly less sensitive to loading.