Secondary Caries Adjacent to Bulk or Incrementally Filled Composites Placed after Selective Excavation In Vitro

Objectives: selective caries excavation (SE) is recommended for deep carious lesions. Bulk fill composites (BF) may be considered to restore SE-cavities. We compared the susceptibility for secondary caries adjacent to BF versus incrementally filled composites (IF) in SE and non-selectively excavated teeth (NS) in vitro. Methods: in 72 extracted human premolars, artificial caries lesions were induced on pulpo-axial walls of standardized cavities. The lesions were left (SE) or removed (NS), and teeth were restored using two BF, GrandioSO x-tra/Voco (BF-Gra) and SDR/Dentsply (BF-SDR), and an IF, GrandioSO/Voco (IF-Gra) (n = 12/group for SE and NS). After thermo-mechanical cycling (5–55 °C, 8 days), teeth were submitted to a continuous-culture Lactobacillus rhamnosus biofilm model with cyclic loading for 10 days. Mineral loss (ΔZ) of enamel surface lesions (ESL), dentin surface lesions (DSL), and dentin wall lesions (DWL) was analyzed using transversal microradiography. Results: ΔZ was the highest in DSL, followed by ESL, and it was significantly lower in DWL. There were no significant differences in ΔZ between groups in DSL, ESL, and DWL (p > 0.05). Regardless of lesion location, ΔZ did not differ between SE and NS (p > 0.05). Conclusions: BF and IF both showed low risks for DWL (i.e., true secondary caries) after SE in vitro, and surface lesion risk was also not significantly different between materials. SE did not increase secondary caries risk as compared with NS. Clinical Significance: the risk of secondary caries was low after selective excavation in this study, regardless of whether bulk or incrementally filled composites were used

OCT evaluation of the internal adaptation of ceramic veneers depending on preparation design and ceramic thickness

OBJECTIVES

In-vitro evaluation of the influence of preparation design and thickness of ceramic veneers on the interfacial bond using optical coherence tomography (OCT).

METHODS

Sixty-four central incisors were randomly assigned to four preparation designs differing from no to complete dentine exposure (n = 16 each): non-prep (NP), minimal-invasive (MI, no dentine exposure), semi-invasive (SI, 50% dentine) and invasive (I, 100% dentine). Ceramic veneers (IPS InLine Veneer) of two thicknesses (0.2-0.5 mm (T1) and > 0.5-1.2 mm (T2)) were etched, silanized, and adhesively luted (Optibond FL, Variolink Veneer). After water storage (37 °C, 21d), thermocycling (2000 cycles, 5°-55 °C), and mechanical loading (2 + 1 million cycles, 50 + 100 N) specimens were imaged by spectral-domain OCT (Telesto II, Thorlabs). Adhesive defects at the ceramic-composite and tooth-composite interfaces were quantified on 35 equidistantly distributed OCT B-scans (length, %). Statistical differences were verified with Wilcoxon-/Mann-Whitney-U-test (α = 0.05).

RESULTS

Adhesive defects appeared in all groups at both interfaces, albeit to differing extents (0.1 - 31.7%). NP and MI veneers showed no significant differences at the interfaces (p_i > 0.05). In groups, SI and I, significantly more adhesive defects appeared at the tooth-composite compared to the veneer-composite interface (p_i ≤ 0.039). The following preparation designs and veneer thicknesses showed differences (p_i ≤ 0.021): Veneer-composite: NP-T1 < I-T1, MI-T1 < I-T1, I-T1 > I-T2; Tooth-composite: NP-T1 < SI-T1, NP-T1 < I-T1, NP-T2 > MI-T2, MI-T1 < SI-T1, MI-T1 < I-T1, SI-T1 < I-T1, MI-T2 < SI-T2, MI-T2 < I-T2.

SIGNIFICANCE

The interface adhesion of ceramic veneers was influenced by the preparation design and the veneer thickness. A ceramic thickness of at least 0.5 mm and a preparation without exposing dentine is advantageous for the interfacial bond.

Hard X-ray phase-contrast-enhanced micro-CT for quantifying interfaces within brittle dense root-filling-restored human teeth

Bonding of resin composite fillings, for example following root-canal treatment, is a challenge because remaining gaps grow and lead to failure. Here, phase-contrast-enhanced micro-computed tomography (PCE-CT) is used to explore methods of non-destructive quantification of the problem, so that countermeasures can be devised. Five human central incisors with damaged crowns were root-filled followed by restoration with a dental post. Thereafter, the crowns were rebuilt with a resin composite that was bonded conventionally to the tooth with a dental adhesive system (Futurabond U). Each sample was imaged by PCE-CT in a synchrotron facility (ID19, European Synchrotron Radiation Facility) with a pixel size of 650 nm. The reconstructed datasets from each sample were segmented and analysed in a semi-automated manner using ImageJ. PCE-CT at sub-micrometre resolution provided images with an impressive increased contrast and detail when compared with laboratory micro-computed tomography. The interface between the dental adhesive and the tooth was often strongly disrupted by the presence of large debonded gaps (on average 34% ± 15% on all surfaces). The thickness of the gaps spanned 2 µm to 16 µm. There was a large variability in the distribution of gaps within the bonding area in each sample, with some regions around the canal exhibiting up to 100% discontinuity. Although only several micrometres thick, the extensive wide gaps may serve as gateways to biofilm leakage, leading to failure of the restorations. They can also act as stress-raising `cracks' that are likely to expand over time in response to cyclic mechanical loading as a consequence of mastication. The observations here show how PCE-CT can be used as a non-destructive quantitative tool for understanding and improving the performance of clinically used bonded dental restorations.

The Influence of Cold Atmospheric Plasma Irradiation on the Adhesive Bond Strength in Non-Demineralized and Demineralized Human Dentin: An In Vitro Study

Purpose:

While aiming at the use of Cold Atmospheric Plasmas (CAPs) in restorative dentistry, the present study intended to assess if plasma irradiation increases the Tensile Bond Strength (TBS) in non-demineralized and demineralized dentin.

Materials and Methods:

Forty-eight human dentin samples were assigned to three different treatment modalities: I: Plasma jet irradiation (CAP I); II: Dielectric barrier discharge plasma treatment (CAP II); and III: No plasma (control). In each group, half of the specimens had previously been demineralized. A fourth generation of adhesive and dental composite was applied to all of the samples. The testing of the TBS was performed after artificial aging.

Results:

In the non-demineralized dentin, the mean TBS values were significantly higher after using CAP II (16.95 MPa) than in the control samples (4.2 MPa; p = 0.001). Significantly higher TBS values were also obtained after irradiating the demineralized dentin with CAP I and CAP II (11.68 and 4.6 MPa) when compared to the control samples (0 MPa; p = 0.003 and 0.038). The differences between both of the plasma sources were only slightly significant (p = 0.05).

Conclusion:

CAPs can potentially enhance the adhesive/dentin interfacial bonding strength, whereby the underlying effects seem to depend on the type of plasma source and the degree of dentinal (de-) mineralization. In the non-demineralized dentin, after a complete caries excavation, dielectric barrier discharge devices might be favorable over the plasma jets, in order to improve the adhesive/dentin interfacial bonding. In contrast, the plasma jets could be more effective in the demineralized dentin after an incomplete caries excavation.

Does Classification of Composites for Network Meta-analyses Lead to Erroneous Conclusions?

Objectives: 

Composites can be classified differently, according to manufacturer information, filler particle size, resin-monomer base, or viscosity, for example. Using clinical trial data, network meta-analyses aim to rank different composite material classes. Dentists then use these ranks to decide whether to use specific materials. Alternatively, annual failure rates (AFRs) of materials can be assessed, not requiring any classification for synthesis. It is unclear whether different classification systems lead to different rankings of the same material (ie, erroneous conclusions). We aimed to evaluate the agreement of material rankings between different classification systems.

Methods: 

A systematic review was performed via MEDLINE, Cochrane Central Register of Controlled Trials, and EMBASE. Randomized controlled trials published from 2005-2015 that investigated composite restorations placed in load-bearing cavitated lesions in permanent teeth were included. Network meta-analyses were performed to rank combinations of composite classes (according to manufacturer, filler particle size, resin-monomers, viscosity) and adhesives. Material combinations were additionally ranked using AFRs.

Results: 

A total of 42 studies (6088 restorations, 2325 patients) were included. The ranking of most material class combinations showed significant agreement between classifications (R2 ranged between 0.03 and 0.56). Comparing material combinations using AFRs had low precision and agreement with other systems. AFRs were significantly correlated with follow-up periods of trials.

Conclusion: 

There was high agreement between rankings of identical materials in different classification systems. Such rankings thus allow cautious deductions as to the performance of a specific material. Syntheses based on AFRs might lead to erroneous results because AFRs are determined by follow-up periods and have low precision.

Fracture Resistance and Cusp Deflection of Lined or Non-lined Composite and Glass Hybrid Restorations Over Residual Demineralized Dentin

PURPOSE

To assess the fracture resistance (FR) and cusp deflection (CD) of lined or non-lined composite (CO) and glass hybrid (GH) restorations over residual demineralized dentin.

MATERIALS AND METHODS

In 48 extracted human premolars, artificial residual demineralized dentin was induced on pulpo-axial walls of standardized cavities. Various restorations were placed over this demineralized dentin: an experimental GH, a composite restoration (OptiBond FL+Tetric EvoCeram) without lining, or composite restorations with non-setting (Hypocal) or setting (Dycal) calcium hydroxide lining. After thermomechanical cycling, groups (n = 12) were compared regarding their CD and FR.

RESULTS

CD did not differ significantly between groups. FR was significantly lower in teeth restored with GH (median: 238 N; 25th/75th percentiles: 191/287 N) than in those restored with lined or non-lined composites (median range: 517-569 N; p < 0.05/Mann-Whitney), which did not differ significantly from each other (p > 0.05).

CONCLUSION

Within the conditions of this in vitro study, CH lining of pulpo-axial walls had only limited impact on CD and FR. GH showed the lowest FR and might not be optimal for restoring deep or extended cavitated lesions.

Margin Integrity and Secondary Caries of Lined or Non-lined Composite and Glass Hybrid Restorations After Selective Excavation In Vitro

OBJECTIVES

For deep carious lesions, selective carious tissue removal (leaving soft dentin close to the pulp) is suggested. Afterward, different restoration materials, such as resin composites or glass hybrids (GHs), can be placed. Many dentists also apply setting or non-setting calcium hydroxide liners before restoration. We compared margin integrity and susceptibility for secondary caries in differently restored premolars in vitro.

METHODS

In 48 extracted human premolars, artificial residual lesions were induced on pulpo-axial walls of standardized cavities. Teeth were restored using a GH (Equia Forte) or adhesively placed resin composite restoration (OptiBond FL and Tetric EvoCeram) without any liner (RC), resin composite restoration with a non-setting calcium hydroxide liner (RC_NCH), or resin composite restoration with a setting calcium hydroxide liner (RC_SCH). After thermomechanical cycling, groups (n=12) were compared regarding their gingivocervical margin integrity (proportion of irregularities, microgaps, gaps >5 μm, overhangs). Teeth were then submitted to a continuous culture Lactobacillus rhamnosus biofilm model. After 14 days, bacterial numbers in biofilms, along tooth-restoration margins and mineral loss (ΔZ) of secondary lesions, were determined.

RESULTS

GH and RC_NCH showed significantly higher proportions of irregularities than RC and RC_SCH (p<0.05/Mann-Whitney). GH also showed significantly more gaps than alternative restorations (p<0.05). Bacterial numbers and ΔZ did not differ significantly between groups (p>0.05).

CONCLUSIONS

GH and composites lined with non-setting calcium hydroxide showed reduced margin integrity compared with non-lined composites or composites lined with setting calcium hydroxide. This did not increase susceptibility for secondary caries.

Directly Placed Restorative Materials

For restoring cavitated dental lesions, whether carious or not, a large number of material combinations are available. We aimed to systematically review and synthesize data of comparative dental restorative trials. A systematic review was performed. Randomized controlled trials published between 2005 and 2015 were included that compared the survival of ≥2 restorative and/or adhesive materials (i.e., no need for restorative reintervention). Pairwise and Bayesian network meta-analyses were performed, with separate evaluations for cervical cavitated lesions and load-bearing posterior cavitated lesions in permanent and primary teeth. A total of 11,070 restorations (5,330 cervical, 5,740 load bearing) had been placed in 3,633 patients in the included trials. Thirty-six trials investigated restoration of cervical lesions (all in permanent teeth) and 36 of load-bearing lesions (8 in primary and 28 in permanent teeth). Resin-modified glass ionomer cements had the highest chance of survival in cervical cavitated lesions; composites or compomers placed via 2-step self-etch and 3-step etch-and-rinse adhesives were ranked next. Restorations placed with 2-step etch-and-rinse or 1-step self-etch adhesives performed worst. For load-bearing restorations, conventional composites had the highest probability of survival, while siloranes were found least suitable. Ambiguity remains regarding which adhesive strategy to use in load-bearing cavitated lesions. Most studies showed high risk of bias, and several comparisons were prone for publication bias. If prioritized for survival, resin-modified glass ionomer cements might be recommended to restore cervical lesions. For load-bearing ones, conventional or bulk fill composites seem most suitable. The available evidence is quantitatively and qualitatively insufficient for further recommendations, especially with regard to adhesive strategies in posterior load-bearing situations. Moreover, different material classifications might yield different findings on the same materials. Future trials should aim for sufficient power, longer follow-up times, and high internal validity to prove or refute differences between certain material combinations. An agreed material classification for future syntheses is desirable.

DBEndo: a web-based endodontic case management tool

Background

The success of endodontic treatment depends—among many other factors—on good documentation. Paper-based records are often difficult to read or incomplete and commercially available tools focus on billing. An electronic record captures the state of treatment at all times. Databases are a common tool in everyday life.

Results

Here, we present a database created for the Charité—Universitätsmedizin Berlin, Germany. Through consistent digital documentation, data analytics of patients, root canal anatomies, instrumentation techniques, efficacy of chemical disinfection, root filling techniques, and corresponding recall success rates, which needed extensive research before, are now easy to perform. Tables and even graphics and data analystics are only one click away and can be exported to other programs.

Conclusions

DBEndo is a database to store and visualise internally, as well as to share endodontic cases online. For academic use we provide the database including all forms and some anonymous data for free at: http://dbendo.charite.de. Through easy import and export of the data, the system is open and flexible.

Are self-adhesive resin cements suitable as core build-up materials? Analyses of maximum load capability, margin integrity, and physical properties

OBJECTIVES

The aim of the present study was to test a self-adhesive resin cement used as core build-up material in comparison to two commercially available core build-up materials.

MATERIALS AND METHODS

Forty human anterior teeth were endodontically treated and fiber post insertion (RelyX Fiber posts) and core build-ups were performed using two core build-up materials applied with an etch-and-rinse adhesive approach (Luxacore Dual-LC and Clearfil Core-CC) and an experimental self-adhesive resin cement (SAR) in two application modes (SAR Handmix and SAR Automix). Samples were subjected to thermo-mechanical loading. Margin integrity was determined using scanning electron microscopy (SEM), and maximum load capability (Fmax) was evaluated. Physical properties of the tested materials were also examined.

RESULTS

Fmax was significantly affected by the core build-up material (p < 0.0005; one-way ANOVA). CC [481 (158) N] revealed significantly higher Fmax compared to LC [226 (80) N], SAR Hand [205 (115), and SAR Automix [197 (134) N] (p < 0.05; Tukey-B). The percentage of margin quality "continuous margin" in enamel after thermo-mechanical loading (TML) differed significantly among groups (p < 0.0005; Kruskal-Wallis); CC demonstrated a significantly higher percentage of margin quality "continuous margin" compared to the other groups. Physical properties were significantly affected by the different core materials (p < 0.0005; ANOVA); CC and LC demonstrated significantly higher flexural strength compared to both SAR groups as well as significantly higher water sorption of both SAR groups compared to CC and LC.

CONCLUSION

Within the limitations of the present in vitro study, we conclude that the investigated experimental self-adhesive resin cement is not suitable as a core build-up material due to the lower maximum load capability, low margin quality, and the data of the mechanical properties.

CLINICAL RELEVANCE

The investigated experimental self-adhesive resin cement cannot be recommended as a core build-up material.

Effect of Industry Sponsorship on Dental Restorative Trials

Industry sponsorship was found to potentially introduce bias into clinical trials. We assessed the effects of industry sponsorship on the design, comparator choice, and findings of randomized controlled trials on dental restorative materials. A systematic review was performed via MEDLINE, CENTRAL, and EMBASE. Randomized trials on dental restorative and adhesive materials published 2005 to 2015 were included. The design of sponsored and nonsponsored trials was compared statistically (risk of bias, treatment indication, setting, transferability, sample size). Comparator choice and network geometry of sponsored and nonsponsored trials were assessed via network analysis. Material performance rankings in different trial types were estimated via Bayesian network meta-analysis. Overall, 114 studies were included (15,321 restorations in 5,232 patients). We found 21 and 41 (18% and 36%) trials being clearly or possibly industry sponsored, respectively. Trial design of sponsored and nonsponsored trials did not significantly differ for most assessed items. Sponsored trials evaluated restorations of load-bearing cavities significantly more often than nonsponsored trials, had longer follow-up periods, and showed significantly increased risk of detection bias. Regardless of sponsorship status, comparisons were mainly performed within material classes. The proportion of trials comparing against gold standard restorative or adhesive materials did not differ between trial types. If ranked for performance according to the need to re-treat (best: least re-treatments), most material combinations were ranked similarly in sponsored and nonsponsored trials. The effect of industry sponsorship on dental restorative trials seems limited.

Resin-based pit-and-fissure sealants: microleakage reduction and infiltration enhancement using a bonding agent

PURPOSE

To evaluate the marginal microleakage and the infiltration ability of pit-and-fissure sealants by applying the conventional sealing technique in comparison to using an additional bonding agent.

MATERIALS AND METHODS

Extracted non-carious permanent molars (n = 60) were first stored in sterile saline solution and then assigned to one of two groups: group C (control) was sealed (Helioseal F) by using the conventional technique, while in group BA (bonding agent), a bonding agent (OptiBond FL) was additionally applied prior to sealing. The teeth were thermocycled (1000 cycles, 5°C to 55°C, dwell time 30 s), then varnished and immersed in 5% methylene blue solution for 24 h. After embedding and sectioning each tooth into 6-12 slices, the presence of microleakage, unfilled areas, and air bubbles trapped in the sealant were assessed with a stereomicroscope.

RESULTS

A higher proportion of microleakage was found under sealants applied without the additional use of the bonding agent. A statistically significant difference in microleakage was noted between the groups (p = 0.045). Regarding the presence of unfilled areas, a statistically significant difference between the groups was observed (p < 0.001), especially since no unfilled areas were found at all in the samples of the group using the bonding agent. Regarding the amount of air bubbles trapped in the sealant, no statistically significant difference was observed between the two groups (p = 0.829).

CONCLUSION

Under these in vitro conditions, sealant procedures using an additional bonding agent applied beforehand significantly improved fissure infiltration and microleakage prevention significantly.

Analysis of resin-dentin interface morphology and bond strength evaluation of core materials for one stage post-endodontic restorations

Purpose

Restoration of endodontically treated teeth using fiber posts in a one-stage procedure gains more popularity and aims to create a secondary monoblock. Data of detailed analyses of so called “post-and-core-systems” with respect to morphological characteristics of the resin-dentin interface in combination with bond strength measurements of fiber posts luted with these materials are scarce. The present study aimed to analyze four different post-and-core-systems with two different adhesive approaches (self-etch and etch-and-rinse).

Materials and Methods

Human anterior teeth (n = 80) were endodontically treated and post space preparations and post placement were performed using the following systems: Rebilda Post/Rebilda DC/Futurabond DC (Voco) (RB), Luxapost/Luxacore Z/Luxabond Prebond and Luxabond A+B (DMG) (LC), X Post/Core X Flow/XP Bond and Self Cure Activator (Dentsply DeTrey) (CX), FRC Postec/MultiCore Flow/AdheSE DC (Ivoclar Vivadent) (MC). Adhesive systems and core materials of 10 specimens per group were labeled using fluorescent dyes and resin-dentin interfaces were analyzed using Confocal Laser Scanning Microscopy (CLSM). Bond strengths were evaluated using a push-out test. Data were analyzed using repeated measurement ANOVA and following post-hoc test.

Results

CLSM analyses revealed significant differences between groups with respect to the factors hybrid layer thickness (p<0.0005) and number of resin tags (p = 0.02; ANOVA). Bond strength was significantly affected by core material (p = 0.001), location inside the root canal (p<0.0005) and incorporation of fluorescent dyes (p = 0.036; ANOVA). CX [7.7 (4.4) MPa] demonstrated significantly lower bond strength compared to LC [14.2 (8.7) MPa] and RB [13.3 (3.7) MPa] (p<0.05; Tukey HSD) but did not differ significantly from MC [11.5 (3.5) MPa].

Conclusion

It can be concluded that bond strengths inside the root canal were not affected by the adhesive approach of the post-and-core-system. All systems demonstrated homogenous hybrid layer formation and penetration into the dentinal tubules in spite of the complicating conditions for adhesion inside the root canal.

A noninvasive treatment of amelogenesis imperfecta

Amelogenesis imperfecta is a hereditary disease affecting the quality and quantity of enamel with a prevalence of 1:700 to 1:14,000. Patients suffer from dental sensitivity and compromised esthetics. The conservative treatment of choice is based on ceramic crowns, but preparation design is unnecessarily destructive to tooth tissue. This case report describes a noninvasive technique with adhesively inserted occlusal composite resin crowns.

Clinical performance of a new biomimetic double network material

BACKGROUND

The development of ceramics during the last years was overwhelming. However, the focus was laid on the hardness and the strength of the restorative materials, resulting in high antagonistic tooth wear. This is critical for patients with bruxism.

OBJECTIVES

The purpose of this study was to evaluate the clinical performance of the new double hybrid material for non-invasive treatment approaches.

MATERIAL AND METHODS

The new approach of the material tested, was to modify ceramics to create a biomimetic material that has similar physical properties like dentin and enamel and is still as strong as conventional ceramics.

RESULTS

The produced crowns had a thickness ranging from 0.5 to 1.5 mm. To evaluate the clinical performance and durability of the crowns, the patient was examined half a year later. The crowns were still intact and soft tissues appeared healthy and this was achieved without any loss of tooth structure.

CONCLUSIONS

The material can be milled to thin layers, but is still strong enough to prevent cracks which are stopped by the interpenetrating polymer within the network. Depending on the clinical situation, minimally- up to non-invasive restorations can be milled.

CLINICAL RELEVANCE

Dentistry aims in preservation of tooth structure. Patients suffering from loss of tooth structure (dental erosion, Amelogenesis imperfecta) or even young patients could benefit from minimally-invasive crowns. Due to a Vickers hardness between dentin and enamel, antagonistic tooth wear is very low. This might be interesting for treating patients with bruxism.

Various irrigation protocols for final rinse to improve bond strengths of fiber posts inside the root canal

Irrigation after post space preparation and its effects on the bond strength of different adhesive strategies are still an issue of interest. The aim of the present study was to investigate the effects of various irrigation protocols (IPs) on the push-out bond strengths of fiber posts. One-hundred and fifty extracted human anterior teeth were divided into three groups (n = 50 each) and endodontically treated. The post space was irrigated before post placement using the following five IPs in each group: IP1 (control): 5 ml of distilled water; IP2: 5.25% sodium hypochlorite (NaOCl) applied with passive ultrasonic irrigation (PUI); IP3: 1% NaOCl applied with PUI; IP4: 18% ethylenediaminetetracetic acid (EDTA) followed by 5.25% NaOCl; and IP5: 2% chlorhexidine (CHX). Fiber posts placement in each group was performed using three different adhesive strategies. A self-etch adhesive system revealed higher bond strength (16.2 ± 6.9 MPa) compared with an etch-and-rinse adhesive (8.5 ± 4.2 MPa) and a self-adhesive resin cement (9.2 ± 4.7 MPa). The use of 18% EDTA/5.25% NaOCl increased the bond strength of the self-adhesive resin cement. Conversely, this IP decreased the bond strength for the etch-and-rinse adhesive system, whilst 1% NaOCl enhanced the bond strength for the same system. Consequently, each adhesive strategy may need to be adapted to a specific IP.

Enamel margin integrity of Class I one-bottle all-in-one adhesives-based restorations

PURPOSE

To evaluate marginal adaptation of Class I restorations in enamel using contemporary one-bottle all-in-one adhesives, stressed by thermocycling (TC) and mechanical loading (ML).

MATERIALS AND METHODS

Ninety-six extracted human molars were prepared (standard Class I cavities: 3 mm deep, 6 mm wide mesio-distally, and 4 mm wide bucco-lingually). Twelve adhesive systems were used: OptiBond FL (OPT), Clearfil SE Bond (CSE) and Adper Prompt L-Pop (PLP) as controls, compared with nine one-bottle all-in-one adhesives - AdheSe One (AHO), Adper Easy Bond (EB), Bond Force (BF), G-Bond (GB), iBond Self Etch (IB), One Coat 7.0 (OC), OptiBond All-in-one (OPA), Clearfil Tri-S-Bond (TSB), Xeno V (XV). All teeth were restored using Filtek Z250 placed in three (one horizontal, two oblique) increments. Enamel margins were evaluated following 21 days of water storage, after thermocycling (2000 cycles: 5°C to 55°C), and after mechanical loading (150,000 cycles, 50 N). After each step, replicas were produced and quantitative SEM margin analysis was performed (200X) using defined criteria.

RESULTS

The median values of % "continuous margin" following TC and ML, respectively, were: OPT(98.6/96.2), CSE(95.4/90.9), BF(81.7/68.1), GB(81.1/65.0), OPA(83.0/68.1), OC(64.1/41.3), TSB(59.3/42.2), EB(57.1/42.6), IB(38.4/27.6), PLP(36.6/21.5), XV(45.0/30.0), AHO(17.7/5.4). Statistical evaluation (Kruskal-Wallis test with Bonferroni adjustment, p < 0.05) revealed the following ranking for ML: OPT=CSE>BF=OPA=GB>OC=EB=TSB=XV =IB=PLP>AHO.

CONCLUSION

All one-bottle all-in-one adhesives exhibited statistically significant lower marginal qualities in enamel compared to the etch-and-rinse system OPF and the two-step self-etching system CSE. The results obtained for GB, OPA and BF, however, were better than for the other all-in-one adhesives.

Effect of pre-heated composites and flowable liners on Class II gingival margin gap formation

PURPOSE

To evaluate the effect of preheated composites (PHC) and flowable liners (FL) on the gingival margin gap formation of Class II composite restorations compared to the placement of room temperature composites (RTC).

MATERIALS AND METHODS

Class II composite restorations were prepared on 40 extracted mandibular third molars, with the gingival margin located 1 mm below the CEJ in dentin. Optibond FL (Kerr), microhybrid Filtek Z-250 (3M ESPE) and Flow-It (Jeneric Pentron) were used to evaluate five study groups: 1) PHC, 130 degrees F/54.4 degrees C; 2) PHC, 155 degrees F/68.3 degrees C; 3) FL cured prior to the first increment composite; 4) FL cured simultaneously with the first increment composite and 5) RTC (Control). Impressions were taken with quick set polyvinyl siloxane impression material, and epoxy resin replicas were evaluated under SEM (200x). Gingival margin adaptation was quantitatively evaluated in terms of percentage of gap formation according to a modified ordinal scoring criteria. All margins were evaluated twice for reliability assessment. A non-parametric Kruskal-Wallis test was used to determine whether significant differences in gap formation existed among the study groups.

RESULTS

A high level of agreement was observed between duplicate measurements of the percentage of gap formation (intra-class correlation = 0.956, p < 0.0001). There was no evidence of a difference among groups defined by placement technique (p = 0.82). Overall, the mean gap-percentage for the 40 margins evaluated was 6.3 (Median = 1.1; SD = 14.8).

CONCLUSIONS

Gingival margin adaptation was not improved relative to the control by any of the placement techniques tested. No significant differences in gap formation were found among the study groups. A high degree of intra-examiner reliability was confirmed.

Restoring strength of incisors with veneers and full ceramic crowns

PURPOSE

The aim was to determine the in vitro fracture resistance of incisors restored with veneers and full ceramic crowns compared to unrestored teeth.

MATERIALS AND METHODS

Seventy intact, extracted human maxillary central incisors were randomized and assigned to 7 groups (n = 10). The teeth in group 1 remained intact (control). The teeth in groups 2 to 6 were prepared and IPS Empress restorations were conditioned and bonded using an adhesive luting cement, Variolink II/Syntac (group 2: labial veneer with incisal overlap, group 3: 3/4 veneer with margin in enamel, group 4: 3/4 veneer with margin in dentin, group 5: crown with margin in enamel, group 6: crown with margin in dentin group 7: veneer on worn tooth. After finishing and polishing, specimens were stored in water and thermocycled for 2000 cycles between 5 degrees C and 55 degrees C. The maximal fracture load of the specimens (40-degree inclination) was determined using the universal testing machine (Zwick) at a constant crosshead speed (0.5 mm/min). The statistical analysis was performed using the Kruskal-Wallis test with Bonferroni correction (p < 0.05). Fracture surfaces were qualitatively analyzed by SEM.

RESULTS

All restored teeth with cervical preparation margins in enamel showed a fracture load not significantly different from the intact teeth (control). Restored teeth with cervical preparation margins in dentin showed a significantly lower fracture load. All restorations showed a fracture load far above 400 N, serving as functional reference for anterior teeth. The failures were predominantly cohesive.

CONCLUSION

For the restoration of tooth strength, defining the finishing lines of veneers and crowns in enamel is recommended. Restorations with finishing lines in dentin resulted in significant loss of strength. Three-quarter veneers with finishing lines in enamel are functionally equal to crowns with the advantage of conserving tooth structure.

Guidelines for the preparation of CAD/CAM ceramic inlays and partial crowns

Ceramic inlays and partial crowns have become scientifically recognized posterior restorations. Their clinical effectiveness depends on the development of durable dental ceramics and luting materials as well as an effective bonding system. Therefore, these factors were in the focus of interest in the past. In contrast, only little attention was given to preparation techniques. However, current studies show that special preparation rules should be followed to ensure best fitting CAD/CAM ceramic restorations and long-lasting clinical success. This paper describes preparation requirements by means of detailed three-dimensional schematic drawings and then deduces the clinical procedure for the preparation of ceramic inlays and partial crowns with standardized preparation instruments.

Interface homogeneity of adhesively luted glass fiber posts

OBJECTIVE

The aim of this study was to light microscopically evaluate the homogeneity of the cement interface of an adhesively luted glass fiber post (GFP) by using a new cement application aid compared to a conventional post cementation method.

METHODS

Twenty artificial root canals (n = 5) received GFP under the following experimental conditions: I = RelyX Unicem applied with a new application aid, II = RelyX Unicem, III = Panavia F 2.0 and IV = Variolink II (groups II-IV with conventional post cementation). From all specimens standardized photographs were taken perpendicularly to the post surface under a light-optical microscope from two opposite sides. The depicted cement interfaces were analysed using surface-analyzing software and related to the complete three-dimensional surface of the cement interface. Non-parametric tests were used to compare median values of the observed inhomogeneities (alpha = 5%).

RESULTS

The median values (%) of inhomogeneities within the cement interface for the cervical, middle, and apical level of analysis were: I = 2, 2, 7; II = 15, 19, 24; III = 8, 16, 39; IV = 11, 16, 29. For the complete post length, median values (%) of inhomogeneities were: I = 4; II = 19; III = 20; IV = 18.

SIGNIFICANCE

The conventional application technique for luting endodontic post results in a large number of voids and bubbles. The combination of a flexible root-canal-shaped application aid achieves a more homogenous cement interface for the self-adhesive luting material tested.

Effectiveness of all-in-one adhesive systems tested by thermocycling following short and long-term water storage

PURPOSE

To evaluate and compare the marginal integrity of in vitro Class V restorations made with all-in-one adhesive systems by thermocycling after different periods of water storage, to provide an analysis of static and quasi-dynamic deterioration in water.

MATERIALS AND METHODS

Standardized Class V cavities (17 groups, 8 specimens each) were prepared in extracted human caries-free anterior teeth. The cavities were filled using 14 all-in-one adhesive systems/composite resin combinations in addition to the multi-bottle adhesive systems Syntac and OptiBond FL (etch-and-rinse technique) and Clearfil SE Bond (self-etching) as controls. The samples were thermocycled after water storage for 21 days, after 1 year and again after 3 years (2000 cycles between 5 and 55 degrees C) and replicas were made before and after each thermocycling treatment (TC) for quantitative marginal analysis in the SEM.

RESULTS

In dentin, marginal adaptation showed no significant differences between all groups after the first TC. After one year of water storage and a second TC, the results for Prompt L-Pop (1999), Adper Prompt L-Pop/Tetric Ceram, and One-up Bond F Plus showed a statistically significant decrease of margin quality 1 (MQ1) score compared to the reference groups. When the all-in-one adhesives G-Bond, AQ-Bond, Hybrid Bond, and One-up Bond F Plus were used, the enamel margins of restorations showed lower percentages of "continuous margins" (p < 0.05) after 1 year of water storage and TC. Of the materials tested after 3 years of water storage and TC, only AQ Bond had a significantly lower MQ1 score.

CONCLUSION

While all materials exhibited deterioration in the MQ1 quality score, the rate of deterioration varied, and the results show that different materials have different deterioration rates after initial vs long-term water storage. The deterioration along margins in dentin was not as extensive as predicted from other studies; however, the results from the enamel margins show that one-bottle all-in-one adhesives seem to be significantly affected by water storage. The results of this study suggest that the all-in-one adhesive group members perform very differently from each other: thus, data need to be explored further at the level of each different adhesive product.

Six-month clinical evaluation of XP BOND in noncarious cervical lesions

PURPOSE

To evaluate the 6-month clinical performance of the etch-and-rinse one-bottle adhesive system XP BOND, used in combination with the composite resin Ceram X duo for the restoration of Class V noncarious cervical lesions (NCCL).

MATERIALS AND METHODS

XP BOND was tested in a total of 40 patients who received two Class V Ceram X duo restorations, Adper Scotchbond 1 XT was used as a control. After cleaning the teeth, the surface of the NCCL was treated using a carbide bur in dentin and a 40-microm diamond bur in enamel with no retentive preparations. The lesions were filled with two increments of Ceram X duo after the application of the respective adhesive by a single operator according to manufacturer's instructions. After 6 months, the retention and the marginal integrity were evaluated.

RESULTS

Thirty-eight of 40 patients were evaluated after 6 months by two clinicians according to modified USPHS criteria, and all restorations using XP BOND were still in place. In the control group (using Adper Scotchbond 1XT), one restoration was lost. The statistical evaluation (chi2 test) showed no significant differences in any of the criteria. No difference of marginal integrity was found between the two adhesive systems.

CONCLUSION

XP BOND meets the ADA success criteria after 6 months.

Influence of disinfectants on dentin bond strength of different adhesive systems

The influence of water disinfectants used in dental unit waterlines on the dentin bonding of different adhesive systems was investigated by using push-out tests. Three hundred and twenty dentin disc specimens were prepared from caries-free human molars. In each specimen, a standardized conical cavity was prepared while cooling with water from a dental unit containing one of three different disinfectants (n=80 each group; A=control: water without disinfectant, B: Alpron neutral, C: Alpron mint, D: Dentosept P). Subsequent rinsing of the cavities was performed With the respective disinfectant. The cavities were filled with the following combinations of dentin adhesives and composites, resulting in 16 subgroups (n=20): Syntac Classic/Tetric Ceram, Clearfil Liner Bond 2V/Luxacore, OptiBond FL/Prodigy and Prime&Bond NT/Spectrum. After polishing the fillings, one half of each subgroup (n=10) was stored in water (37 degrees C) for 24 hours. The other half was stored in water (37 degrees C) for 180 days and additionally thermocycled (2000 cycles at 5/55 degrees C). The bond strength was then measured by push-out tests. Statistical analysis of the data was carried out using ANOVA and pairwise t-tests (Significance level p < or = 0.01). The disinfectants showed no significant influence on the loads required for debonding of Syntac Classic/Tetric Ceram, Clearfil Liner Bond 2V/Luxacore and OptiBond FL/Prodigy as compared to the controls. However, the use of disinfectants in the water supply of a dental unit decreased dentin bond strength in the specimens filled with Prime&Bond NT/Spectrum. Disinfectants in the water of dental unit waterlines may have an influence on dentin bonding, depending on the adhesive system used.

Intracoronal bleaching of discolored non-vital teeth

This clinical study compared the effectiveness of bleaching non-vital teeth with an open pulp chamber during bleaching using 10% carbamide peroxide compared to the modified walking bleach technique and extracoronal bleaching. Sixty discolored, non-vital teeth were treated. They were divided into three groups. Each group was treated with one of the bleaching materials and methods: extracoronally using 10% carbamide peroxide for two weeks as negative control (Group A), intracoronally using sodium perborate mixed with 3% hydrogen peroxide (modified walking bleach technique) (Rotstein, Mor & Friedman, 1993) for four weeks (Group B) and intracoronally and extracoronally using 10% carbamide peroxide for two weeks (Group C) (Liebenberg, 1997). Tooth color was measured at baseline, (BL), immediately post-bleaching (IP) and six months post-bleaching (SP) with a colorimeter (Castor, Sigma, Germany) using a tooth-positioning jig. The color was determined according to the CIELAB system, which records lightness as L* and chromaticity coordinates as a* and b*. The difference in L* and b* among the three groups was significant between BL and IP examination. The post-bleaching, whitening effect in Group C was significantly better, but after six months, in Group C, it was as effective as in Group B.

The influence of a simplified application technique for ceramic inlays on the margin quality

The adhesive luting technique for ceramic inlays requires a sequence of multiple steps that are cumber-some and time consuming. Furthermore, modifications of dentin bonding procedures may negatively influence the margin quality of ceramic inlays with cervical dentin finishing lines.

PURPOSE

The objective of this study was to test the effect of a new, simplified procedure for dentin bonding on the margin quality of ceramic inlays.

MATERIALS AND METHODS

Thirty-two MOD inlay cavities with cervical finishing lines in dentin were prepared into premolars. They were randomly divided into four groups (n = 8): In the balanced design, one parameter was the inlay material (Empress/Cerec) and the other the polymerization of the dentin bonding agent, before insertion of the inlay (P+) and after insertion of the inlay (P-). All inlays were inserted with Variolink II in combination with an enamel and dentin conditioning universal bonding agent (Etch & Prime 3.0). Two parameters were used to determine the inlay quality: (1) the fit, measured by the difference of the insertion depth into the cavity between try-in and cementation, and (2) a quantitative margin analysis in the SEM at a magnification of 200x, performed for the cervical segment before and after thermocycling, using epoxy replicas.

RESULTS

In all four groups the inlays were > 5 microns deeper in the cavities than at the try-in session. This is explained by the substance loss from the etching. The measured difference for Cerec inlays inserted in cavities, where the bonding agent was not polymerized prior to insertion, was significantly larger. Margin analysis of the cervical segment revealed no statistical differences (P < 0.01) for both criteria tested. The median values for all groups were 100% for clinical acceptable margin and 0% for marginal opening.

CONCLUSION

By using the universal bonding agent, high margin qualities on dentin and enamel are obtained with ceramic inlays even with the simplified approach.

Marginal adaptation of compomer Class V restorations in vitro

PURPOSE

The purpose of this in vitro study was to determine the marginal adaptation of different adhesives, including recently developed self-etching primers, in combination with compomers in Class V cavities.

MATERIALS AND METHODS

In 80 extracted human teeth, divided into 10 groups of 8, Class V cavities were prepared (ca. 4 mm high, 3 mm wide, and 1.5 mm deep) with one half of the margin length in dentin. The one-bottle adhesives Prime & Bond 2.1, Syntac SC, and Espe OSB, and the self-etching primers Rasant F 2000 and Prompt L Pop were used in combination with compomers. Before and after thermocycling (TC), replicas were taken and a quantitative margin analysis using the SEM was performed at a magnification of 200x using defined criteria.

RESULTS

The statistical analysis using Kruskal-Wallis and Bonferroni tests showed a significantly (p < 0.05) better marginal adaptation in enamel and dentin for the self-etching primers, and when the one-bottle adhesives were used in combination with the total-etch technique.

CONCLUSION

Self-etching primers improve the marginal adaptation of compomer restorations in enamel.

Improving cervical restorations: a review of materials and techniques

INTRODUCTION

There is a great variety of cervical lesions and an increased need for treatment because patients complain either about esthetics, hypersensitivity, or even food impaction. The cumulative effects of noncarious dental tissue loss are increasingly evident within any population. The prevalence of these noncarious lesions has been estimated at between 31% and 56%, with 85% of the population showing some loss of tooth structure in the cervical area. Since more elderly patients will keep their teeth for a longer time, the problems regarding the cervical areas of the teeth will increase. Therefore, the challenge for the dentist is rather substantial, since it has been shown that the longevity of these cervical restorations is not as great as that of other restorations. The purpose of this review is to summarize some facts about cervical lesions, the different tooth-colored restorative materials and their application, and the assessment of the clinical performance of these materials.

Influence of incorrect application of a water-based adhesive system on the marginal adaptation of Class V restorations

PURPOSE

To determine the influence of incorrectly performed steps during the application of the water-based adhesive system OptiBond FL on the marginal adaptation of Class V composite restorations.

MATERIALS AND METHODS

In 96 extracted human teeth Class V cavities were prepared. Half of the margin length was situated in dentin. The teeth were randomly divided into 12 groups. The cavities were filled with Prodigy resin-based composite in combination with OptiBond FL according to the manufacturer's instructions (Group O) and including several incorrect application steps: Group A: prolonged etching (60 s); Group B: no etching of dentin; Group C: excessive drying after etching; Group D: short rewetting after excessive drying; Group E: air drying and rewetting; Group F: blot drying; Group G: saliva contamination; Group H: application of primer and immediate drying; group I: application of only primer; group J: application of only adhesive; Group K: no light curing of the adhesive before the application of composite. After thermocycling, replicas were taken and the margins were quantitatively analyzed in the SEM. Statistical analysis of the results was performed using non-parametric procedures.

RESULTS

With exception of the "rewetting groups" (D and E) and the group with saliva contamination (G), all other application procedures showed a significantly higher amount of marginal openings in dentin compared to the control group (O). Margin quality in enamel was only affected when the primer was not applied.

Crystal precipitation on dentin by poly(acrylic acid) solutions containing SO4(2-) ions

The ability of four different 40% poly(acrylic acid) (PAA) solutions, containing 4 or 6 wt-% of either Na2SO4 or (NH4)2SO4, to cause precipitation of CaSO4 on dentin surfaces was investigated. Each treatment consisted of exposing the dentin to one of the four solutions for either 1 or 2 min and was followed by a water rinse (1 min) and air drying (30 sec). The treated dentin surfaces were then evaluated in a scanning electron microscope (SEM), which showed that crystals precipitated on the dentin with these solutions. Of the four investigated PAAs, one performed better than the others with regard to crystal precipitation and blockage of the tubules. This solution was selected for additional studies of the effects of different PAA concentrations (10%, 20%, 30%, 40%, and 50%). In these solutions, 4 and 6 wt-% of either Na2SO4 or (NH4)2SO4 were dissolved. Additional dentin surfaces were then treated with these solutions as described earlier and evaluated in an SEM. This evaluation showed that solutions containing 30-50% PAA resulted in optimized crystal formation for all the different sulfate solutions and that the optimization occurred within 1 min. Besides optimizing crystal precipitation, these mixtures also minimized the frequency of open dentinal tubules.

[Effects of dentin bonding agents on the proximal margins of ceramic inlays]

Ceramic inlays have shown good marginal seal as long as the margins of the cavities are located in enamel. The purpose of this study was to investigate the marginal seal of ceramic inlays with the cervical margins situated in dentin and to determine the effectiveness of dentin bonding agents. Sintered ceramic inlays were adhesively luted either without dentin bonding agents or with the use of Gluma or Miragebond. After thermocycling and incubation in a colored dye the penetration depth of the dye was measured on sequential sections. The used dentin bonding agents did not improve marginal seal. The glass ionomer cement base was able to prevent further penetration in most of the cases when deep leakage occurred. Unless a tight marginal seal in dentin can be achieved, the indication for adhesively luted inlays must be limited to cavities with margins located in enamel.

[Time of extraction and cavity position in in-vitro tests of dentin adhesives]

Cylindrical cavities were prepared in different tooth segments (coronal, cervical and radicular) and at different times (1 hour, 1 day, 1 week and 1 month) after extraction into face-ground dentin surfaces of extracted teeth. The cavities were filled with composite resin materials using different dentin adhesives. Before and after thermocycling (TC) the marginal adaptation was evaluated using defined criteria. The statistical evaluation did not show any significant differences (p greater than 0.01) after TC within the different groups of dentin adhesives. For in vitro tests of dentin adhesives neither the position nor the time of extraction decisively influences the process.

[Comparison of two cavity preparations to examine the efficacy of dentin adhesives]

Cylindrical cavities and class V cavities were treated with six different dentin adhesives before filling them with composites. Cavity margins were studied quantitatively with defined criteria before and after alternating thermal stress tests in a scanning electron microscope. In both cavity preparations groups of dentin adhesives with significantly different efficacies (p 0.05) were identified. The efficacy of dentin adhesives and their effect on marginal adaptation of composite materials in dentin can be determined rather easily in cylindrical cavities.

Quantitative margin analysis in the scanning electron microscope

Interface between restorative materials and tooth hard substances must be morphologically as perfect as possible to avoid plaque accumulation and subsequent secondary caries or pulpal diseases. Therefore the marginal behavior of restorations is an important parameter to predict their longevity. Morphologically, the quality of margins is characterized by different well defined criteria. Using a replica technique it is possible to assess the complete marginal circumference of restorations in the SEM. Margins of restorations show a large variety of their morphology. This publication describes a method to quantify the quality of dental restorations. The restoration margins are traced on the SEM screen with a digitizer and an interface to measure the margin's length. Simultaneously the margin quality is assessed and assigned to the corresponding lengths. The % distribution of the quality criteria for each restoration is then calculated. Using a comparative light microscope, the replicas are aligned and mounted identically in the SEM for longitudinal studies. The results presented are limited to tests for the accuracy of the method. Using 5 criteria to characterize the margin quality, it was found that the difference between two measurements by the same operator, 4 weeks apart was 3% +/- 2.6%. The largest difference for one group was 9%. In another accuracy test where 4 criteria for margin characterization were used, the difference between two measurements was 1.9% +/- 0.9%. The largest difference between two groups found was 3.4%. This method can be used for longitudinal studies in vivo, but also for in vitro screening tests with new materials.