Enhancing subgingival margin restoration: a comprehensive review and meta-analysis of deep margin elevation's impact on microleakage.

INTRODUCTION: Restorative dentistry faces complex challenges with deep proximal surface destruction, requiring novel approaches like DME (Deep Margin Elevation). In order to achieve the best results while treating severe tooth damage, this study examines the advantages, disadvantages, and possible collaborations of different treatments. AIMS: This systematic review investigates the efficacy of DME as an adjunctive procedure in restorative dentistry, specifically focusing on its impact on microleakage. METHODS: The study adheres to PRISMA guidelines and employs the PICOS framework for eligibility criteria. 394 potentially qualifying studies were discovered and thorough literature search was carried out via databases. After applying inclusion criteria, 7 studies were included in the analysis. Articles were selected based on criteria that included indirect restoration and performing DME and were compared with indirect restorations without DME. Composite resin was used for DME. Other materials for DME performing, including GI and composite flow, were systematically reviewed. Data analysis was done by biostat software (α = 0.05). RESULTS: The meta-analysis of selected studies reveals a statistically significant positive effect of DME on reduction of microleakage (p = 0.001). CONCLUSION: The results of this study underscore the potential of DME in addressing subgingival margin challenges and provide valuable insights for restorative dentistry practices.

Comparison of bond strength of self-adhesive and self-etch or total-etch resin cement to zirconia: A systematic review and meta-analysis.

The aim of this study was to systematically compare the bond strength of self-adhesive and self-etch or total-etch resin cement to zirconia. The PubMed, ISI (all), and Scopus databases were searched for the selected keywords up to November 1, 2021, without date or language restrictions. In vitro studies comparing the bond strength of self-adhesive and self-etch or total-etch resin cement to zirconia were eligible for inclusion in the study. The selected articles were divided into four groups based on the type of resin cement and the storage time. Statistical analysis was performed using the Biostat Comprehensive Meta-Analysis Software version 2 (α = 0.05). The effect of conventional cement ( Glass Ionomer (GI), Resin Modified Glass Ionomer (RMGI) and zinc phosphate) was analyzed using descriptive analysis. The initial search yielded 376 articles, of which 26 were selected after a methodological assessment. Two reviewers independently extracted data and assessed the risk of bias. The results showed that the immediate or delay bond strength of the self-adhesive resin cement to zirconia has no significant difference with the bond strength of self-etch resin cement to zirconia. The immediate and delay bond strength of total-etch cement-zirconia was significantly lower than that of self-adhesive cement-zirconia (P = 0.00). A descriptive analysis of the selected articles showed that the bond strength of self-adhesive resin cement to zirconia was significantly higher than total-etch cement. The results of the meta-analysis showed that both self-adhesive and self-etch resin cement (if applied according to their manufacturer's instruction) are suitable for bonding to zirconia.

Effect of Chlorhexidine on Immediate and Delayed Bond Strength between Resin and Dentin of Primary Teeth: A Systematic Review and Meta-Analysis.

Objectives: The purpose of this study was to systematically review the literature and use meta-analysis to investigate whether chlorhexidine (CHX) application after acid etching as an adjunct treatment has any influence on the immediate and delayed bond strength to primary dentin. Materials and Methods: In this review, PubMed, ISI (all data bases), Scopus and Cochrane were searched according to the selected keywords up to April 30, 2018. The full texts of all published articles that met our primary inclusion criteria were obtained. The studies were analyzed in two parts: in vitro studies that evaluated the effect of CHX application during the bonding procedures (application after acid etching) on immediate and delay dentin bond strength of resin-dentin interface. Results: The initial search yielded 214 publications, of which 8 were selected after thorough methodological assessment. None of the clinical studies fulfilled the eligibility criteria. Our results indicated that in comparison to the control group, CHX significantly reduced immediate resin-dentin bond strength (P=0.043). These values were increased after aging (P<0.001). Conclusion: Based on this invitro Meta-analysis CHX application, improve resin-dentin bond strength durability in primary teeth.

Retrospective evaluation of the clinical performance of direct composite restorations using the snow-plow technique: Up to 4 years follow-up.

BACKGROUND: To evaluate the clinical performance of direct composite restorations using the snowplow technique with up to 4 years of follow-up. MATERIAL AND METHODS: In this retrospective study, 101 class II composite restorations which were placed in permanent molars (n = 19) and premolars (n = 82) in 85 patients by the snowplow technique, were evaluated according to the modified USPHS criteria. A Kaplan-Meier analysis with a 95% confidence level was used to calculate the survival probability. RESULTS: Of the 101 teeth examined, tooth failure was identified in 8 teeth due to secondary caries (3%), marginal gap (2%), marginal discoloration (1%) and restoration breakdown (2%) which required replacement of the whole restoration. Sixteen teeth achieved a Bravo score and just needed to be repaired. The results of the Kaplan-Meier analysis regarding overall survival estimates of composite-treated teeth using the snowplow technique at 1-, 2-, 3- and 4- year follow-ups were 99%, 96.2%, 89.6% and 79% respectively. The median survival times of composite restorations using the snowplow technique were 46.49 ± 11.47 month. CONCLUSIONS: This retrospective study showed that application of a flowable composite as a liner using the snowplow technique does not improve the clinical survival of posterior composite restorations. Key words:Snowplow, composite restoration, success rate.

Are self-etch adhesives reliable for primary tooth dentin? A systematic review and meta-analysis.

The purpose of this study was to systematically evaluate the dentin bond strength of etch-and-rinse and self-etch adhesives to primary teeth. In this study, PubMed, ISI (all databases), Scopus, and Cochrane Database were searched according to the selected keywords up to May 11, 2016. The full texts of published articles that appeared to meet the primary criteria for inclusion in this study were obtained. Due to the variation in the methods used, the studies were divided into 2 groups: Group 1 - studies that evaluated the micro-tensile bond strengths (MTBSs) of two-step etch-and-rinse adhesives and two-step self-etch adhesives and Group 2 - studies that evaluated the MTBSs of two-step etch-and-rinse adhesives and one-step self-etch adhesives. The initial search yielded 1447 publications. After a methodological assessment, 8 publications were selected. The results of this study showed that the MTBS of the etch-and-rinse adhesives and the two-step self-etch adhesives were similar (P = 0.34), and both were significantly higher than that of the one-step self-etch adhesive (P = 0.001). This meta-analysis showed that the application of two-step self-etch adhesives performs well when used for primary dentin and can be used to save time in pediatric dentistry.

Comparison of the shear bond strength of self-adhesive resin cements to enamel and dentin with different protocol of application.

AIM: The aim of the present study was to determine the shear bond strength of self-adhesive resin cements to enamel and dentin with and without surface treatments, and compare them with conventional resin cement as the control group. METHODS: In this experimental study, buccal and lingual surface of the thirty sound human premolars were polished in order to obtain a flat surface of enamel (E) in buccal, and dentin (D) in lingual. Sixty feldspathic ceramic blocks (2×3×3 mm) were prepared and randomly divided into six groups (n=10). Each block was cemented to the prepared surface (30 enamel and 30 dentin surface) according to different protocol: E1 and D1; RelyX ARC as control group, E2, D2; RelyX Unicem, E3, D3; acid etching +RelyX Unicem. The specimens were termocycled and subjected to shear forces by a universal testing machine at a cross head speed of 0.5 mm/min. The mode of fracture were evaluated by stereomicroscope. Data were analyzed with descriptive statistical methods using SPSS version 15. One-way ANOVA, and post hoc Tukey tests were used to compare bond strengths between the groups with different adhesives at α=0.05. RESULTS: Statistical analysis showed no significant differences within the enamel subgroups, but there were significant differences within the dentinal subgroups, and statistically significant differences were found between the groups D1and D3 (p=0.02). Comparison between similar enamel and dentinal subgroups showed that there was a significant difference just between the subgroups E3 and D3 (p=0.01). CONCLUSION: Elective etching of enamel did not lead to significant increase in the shear bond strength of RelyX Unicem in comparison to RelyX ARC. On the other hand, elective etching of dentin reduces the bond strength of RelyX Unicem with the dentin.

Comparing the effect of a desensitizing material and a self-etch adhesive on dentin sensitivity after periodontal surgery: a randomized clinical trial.

OBJECTIVES: This double-blind randomized placebo-controlled clinical trial evaluated the ability of a desensitizing agent and a self-etch adhesive on cervical dentin sensitivity (CDS) after periodontal surgery. MATERIALS AND METHODS: Ninety hypersensitive teeth of 13 subjects were included in the study. After periodontal surgery, the teeth of each posterior sextant treated with one of the following materials: G1: Clearfil S3 Bond (Kuraray Dental), G2: Gluma Desensitizer (Heraeus Kulzer), and G3: placebo (water). The sensitivity was assessed using evaporative stimuli before treatment (baseline, T0), 1 day after treatment (T1), after 1 week (T2), and after 1 month (T3) according to visual analog scale (VAS). RESULTS: Following the treatment, all the 3 groups showed significant reduction of CDS in T1 compared to T0. Reduction of CDS between T1 and T2 was observed only in G1 but there was no significant difference between T2 and T3 in this group. Although we observed a significant difference in T3 compared to T1 and T2 in G2 and G3, comparison of treatment groups in each assessment time showed a significant difference only in T3. According to paired comparison, this was due to the difference between G2 and G3. CONCLUSIONS: Dentin sensitivity following periodontal surgery will decrease spontaneously over time, but treating the sensitive teeth with Gluma Desensitizer and Clearfil S3 Bond can have some benefits.

Effect of Chlorhexidine and Ethanol on Microleakage of Composite Resin Restoration to Dentine.

OBJECTIVE: To evaluate the effect of chlorhexidine and ethanol on microleakage of composite resin restoration to dentine. METHODS: Class II cavities with dentinal margin were prepared on 96 premolar teeth. All specimens were acid-etched, rinsed and dried. Then the samples were randomly divided into four groups according to pre-treatment of the dentine: no treatment (control group); treatment with 100% ethanol for 60 s (group 2); treatment with 2% chlorhexidine for 60 s (group 3); 100% ethanol for 60 s and then 2% chlorhexidine for 60 s (group 4). After dentine treatment, each group was bonded and restored with a universal micro hybrid composite resin, according to the manufacturers' recommendation. Microleakage was evaluated by dye extraction method in two subgroups, immediately (24 h) and after 6 months in storage. Scan electronic microscope analyses for two samples of each group were also conducted. Data were analysed by two-way analysis of variance and Tukey test. RESULTS: The lowest and the highest amount of microleakage were observed in the ethanol group and in the control group, respectively. There were significant differences in microleakage among the groups (P = 0.003) and between measurement times (P = 0.001). For each storage time, the control group showed significant differences from the other groups and there were no differences between the other groups. CONCLUSION: Ethanol-wet bonding and chlorhexidine application may have potential benefits in lowering the occurrence of microleakage in the long term.

Laboratory evaluation of the effect of unfilled resin after the use of self-etch and total-etch dentin adhesives on the Shear Bond Strength of composite to dentin.

BACKGROUND: Based on the frequent application of composite resins as tooth-colored fillings, this method is considered a viable alternative to dental amalgam. However, this method has the low bond strength of the composite to dentin. To solve this issue, various dental adhesive systems with different characteristics have been developed by dentistry experts. AIM: To assess the effect of an additional layer of unfilled resin in self-etch and total-etch dentin adhesives on the shear bond strength (SBS) of composite to dentin. Moreover, we assessed the effects of sample storage in artificial saliva on the SBS of composite to dentin. METHODS: Methods: This experimental study was conducted on 160 freshly extracted human first or second premolar teeth, which were randomly divided into 16 groups. The teeth were prepared from Mashhad University of Medical Sciences, Mashhad, Iran (2008-2009). Scotchbond Multi-purpose (SBMP), single bond (SB), Clearfil SE Bond, and Clearfil S3 Bond were applied to dentin surface with or without the placement of hydrophobic resin (Margin Bond) in accordance with the instructions of the manufacturers. To expose the coronal dentin, the teeth were abraded with 600 grit SiC paper. Immediately after restoration, half of the samples were tested in terms of SBS, while the other samples were evaluated in terms of SBS after three months of storage in artificial saliva. SBS rates of dental composites evaluated by universal testing machine and samples were studied by optical stereomicroscopy to verify the failure type. Data analysis was performed in SPSS V.16 using Kolmogorov-Smirnov test, independent-samples t-test, ANOVA, and Duncan's logistic regression test. RESULTS: In this study, a significant reduction was observed in the SBS rates of SB and S3 bond adhesive systems after storage with and without hydrophobic resin (p>0.000). Without storage in normal saline, a significant increase was observed in the SBS rate of the SE bond (p=0.013). In addition, SBS rate of SBMP significantly increased after storage with hydrophobic resin (p=0.001). Finally, the highest and lowest rates of SBS were observed in the SE and S3 bonds in all the experimental groups, respectively. CONCLUSION: The effects of using a hydrophobic resin layer on shear bond strength values seem to be effective. The mild self-etch adhesive exhibited the best resin-dentine bond strength after aging.

Evaluation of the efficacy of flowable composite as lining material on microleakage of composite resin restorations: A systematic review and meta-analysis.

OBJECTIVE: The efficacy of flowable composite in improving marginal adaptation or reducing microleakage is not fully understood. The purpose of this study was to systematically evaluate existing evidence to verify whether an application of flowable composite as a liner provided less microleakage in Class 2 composite restorations. METHOD AND MATERIALS: PubMed, ISI (Web of Science), and Scopus databases were searched according to the selected keywords, up to 15 Feb 2015, without any restriction on date or language. Full texts of published articles that seemed to meet primary criteria for inclusion in this research were obtained. Data of studies were extracted if they were assessed as high or moderate level of evidence. Due to the variation of methods used in different studies, they were divided into five groups: groups 1 and 2, studies that evaluated the effect of flowable composite as a liner on dentinal or enamel margins and applied flowable composite on all of the cavity wall margins; groups 3 and 4, studies that evaluated the effect of flowable composite as a liner on dentinal and enamel margins and applied flowable composite only on gingival margin; and group 5, clinical studies. RESULTS: The initial search yielded 1,370 publications. After hand searching, six extra studies were included in the review. The abstracts of all were read independently by AB and SG. After methodologic assessment and evaluation of the level of evidence, 18 studies were selected for this study. The results of this study indicate that flowable composite liners have no significant effect on microleakage of composite restorations in all of five groups. CONCLUSION: Application of flowable composite as a liner in composite restorations cannot reduce microleakage or improve clinical performance.

Effect of amalgam corrosion products in non-discolored dentin on the bond strength of replaced composite resin.

OBJECTIVES: To evaluate the effect of amalgam corrosion products in non-discolored dentin on the bond strength of replaced composite resin. MATERIALS AND METHODS: One hundred and sixty-one Class I cavities were prepared on extracted premolars and divided into seven groups. Group 1: Light-cured composite; Groups 2, 3, and 4: Amalgam stored in 37°C normal saline for respectively 1, 3, and 6 months and then replaced with composite leaving the cavity walls intact. Groups 5, 6, and 7: Identical to Groups 2, 3, and 4, except the cavity walls were extended 0.5 mm after amalgam removal. Eighteen specimens from each group were selected for shear bond strength testing, while on remaining five samples, elemental microanalysis was conducted. Data were analyzed using Mann-Whitney and Freidman (α = 0.05). RESULTS: There was a significant difference between Groups 1 and 4 and also between Group 1 and Groups 5, 6, and 7. However, Groups 1, 2, and 3 showed no significant difference regarding bond strength. Bond strengths of Group 4 was significantly less than Groups 2 and 3. However, Groups 5, 6, and 7 showed similar bond strength. There was no difference among all groups in terms of metal elements at any storage times.

Evaluation of the effect of diacetyl morphine on salivary factors and their changes after methadone therapy.

OBJECTIVES: Psychoactive drugs are responsible for pathological changes in the mouth including dental caries, which most troublesome. The aim of the present study was to evaluate the effect of heroin on several salivary factors which are involved in the oral health and their changes after methadone maintenance therapy (MMT). MATERIALS AND METHODS: Forty patients with heroin abuse history, who referred to Imam Reza Hospital for MMT were included. Saliva sampling was carried out two times; at the first visit (time 1) and repeated 1 month after MMT (time 2). The saliva was analyzed immediately to evaluate the total volume, Ph, CPR, the Uric acid concentration, nitric oxide and antioxidant capacity. RESULTS: The mean values for saliva volume, pH, CRP, Uric acid, antioxidant and nitric oxide were 0.38 ± 0.14, 7.63 ± 1.22, 5.2 ± 2.3, 1.47 ± 0.8, 0.80 ± 0.23, and 0.26 ± 0.03, respectively at first visit and 0.34 ± 0.22, 7.37 ± 1.01, 6.1 ± 2.6, 2.18 ± 0.9, 0.74 ± 0.3 and 0.29 ± 0.08 after 1 month of MMT. These values are below the normal ranges; however, there was no significant difference between two times in term of saliva volume, pH and saliva component (p > 0.05). CONCLUSION: Heroin addiction changed the effective salivary factors and therefore could negatively contribute to oral health. These factors were not return to the normal range after 1 month of MMT. Physicians should be informed about focusing on oral health in patients under MMT.

Randomized clinical evaluation of the effect of chlorhexidine on postoperative sensitivity of posterior composite resin restorations.

OBJECTIVES: Evaluation of postoperative sensitivity in posterior teeth restored with etchand- rinse adhesive and composite resin after application of 2% chlorhexidine solution. METHOD AND MATERIALS: Thirty participants with similar dental caries on both sides of the jaws were selected. After cavity preparation, each tooth was randomized to one of the following restoration methods. Teeth in the control group were restored using etch-and-rinse resin adhesive (Single Bond, 3M ESPE) and universal microhybrid composite resin (Filtek Z250, 3M ESPE). Restoration of teeth in the experimental group was similar to the control group except that 2% chlorhexidine solution (Concepsis, Ultradent) was applied on the etched dentin for 60 seconds. Subjects were recalled for evaluation of postoperative sensitivity at 1 day, 1 week, 1 month, and 6 months. Data were analyzed by Fisher exact test (α = .05). RESULTS: The experimental group showed significantly less postoperative sensitivity (8 teeth) compared with the control group (20 teeth) at the 1-day recall (P < .05; Fisher exact test). Conventional restorations were comparable to teeth treated with chlorhexidine at other recall times (P > .05). CONCLUSION: Chlorhexidine significantly decreased immediate postoperative sensitivity of posterior teeth restored by composite resin.

The degree of color change, rebound effect and sensitivity of bleached teeth associated with at-home and power bleaching techniques: A randomized clinical trial.

AIM: The purpose of the present randomized clinical trial was to evaluate the color change, rebound effect and sensitivity of at-home bleaching with 15% carbamide peroxide and power bleaching using 38% hydrogen peroxide. MATERIALS AND METHODS: For bleaching techniques, 20 subjects were randomized in a split mouth design (at-home and power bleaching): In maxillary and mandibular anterior teeth (n = 20). Color was recorded before bleaching, immediately after bleaching, at 2 weeks, 1, 3 and 6 month intervals. Tooth sensitivity was recorded using the visual analog scale. The Mann-Whitney test was used to compare both groups regarding bleaching effectiveness (ΔE1), rebound effect (ΔE2) and color difference between the rebounded tooth color and unbleached teeth (ΔE3) while the Wilcoxon compared ΔE within each group. Distribution of sensitivity was evaluated using the Chi-square test (α =0.05). RESULTS: There was no significant difference between groups regarding ΔE1 and ΔE3 (P > 0.05). Even though, ΔE2 showed no significant difference between groups after bleaching as well as at 2 week, 1 month and 3 month follow-up periods (P > 0.05). Although, significant difference was found in ΔE2 (P < 0.05 Mann-Whitney) between two methods after 6 months and a high degree of rebound effect was obtained with power bleaching. Within each group, there was no significant difference between ΔE1 and ΔE3 (P < 0.05 Wilcoxon). The distribution of sensitivity was identical with both techniques (P > 0.05). CONCLUSION: Bleaching techniques resulted in identical tooth whitening and post-operative sensitivity using both techniques, but faster color regression was found with power bleaching even though color regression to the baseline of the teeth in both groups was the same after 6 months.

Effect of different conditioning protocols on the adhesion of a glass ionomer cement to dentin.

AIM: The purpose of this study was to assess the effect of different surface treatments on the shear bond strength (SBS) of a resin modified glass ionomer cement (RMGIC) to dentin. METHODS AND MATERIALS: Forty human third molar teeth were randomly divided into four groups (n=10). The occlusal enamel was removed to obtain a flat surface of dentin. Each group was treated as follows: Group 1: 10% polyacrylic acid (positive control); Group 2: 37% phosphoric acid followed by 5% sodium hypochlorite (NaOCl); Group 3: 1.1% APF gel; and Group 4: no conditioning (negative control). Fuji II LC glass ionomer was bonded to dentin using a cylindrical mold. Samples were thermocycled and debonded using a shear force with a crosshead speed of 0.5 mm/min. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey tests (a = 0.05). RESULTS: The mean SBS in Groups 1 through 4 were 11.562+/-3.148, 8.060+/-1.781, 8.830+/-1.554, and 3.074+/-0.784 (MPa), respectively. There were significant differences in the SBS between Group 1 with other groups (P<0.05). There were no statistically significant differences between Groups 2 and 3, but the SBS of both of them were significantly higher than that of Group 4 (P<0.05). CONCLUSION: Although the dentin SBS of Fuji II LC after conditioning with APF and phosphoric acid followed by NaOCl was greater than the unconditioned group (Group 4), polyacrylic acid yielded the best result. CLINICAL SIGNIFICANCE: Proper conditioning of dentin is effective in promoting close adaptation of RMGIC to dentin.

Effect of posts on the fracture resistance of load-cycled endodontically-treated premolars restored with direct composite resin.

AIM: The aim of this study was to investigate the fracture resistance and failure mode of premolars restored with composite resin using various prefabricated posts. METHODS AND MATERIALS: Sixty sound maxillary premolars were divided into four equal sized groups. All but the control group received endodontic treatment followed by placement of mesiodistocclusal (MOD) composite restorations (Tetric Ceram) as follows: Group T = no post, Group DT = fiber reinforced composite (FRC) post (DT Light), Group FL = prefabricated metal post (Filpost). The control group (C) had no cavities prepared. After thermal and load cycling, static load was applied at a 30 degrees angle until fracture. Failure modes were categorized as restorable and non-restorable. Data were analyzed using the analysis of variance (ANOVA) and Duncan tests (a = 0.05). RESULTS: The mean values of fracture loads (N) for all groups were: C (880+/-258); T (691+/-239); DT (865+/-269); and FL (388+/-167). Statistically significant differences (P<0.05) were observed for all groups except between groups C and DT. The Chi Square test showed failure modes in groups C and DT were mostly restorable. The most non-restorable fractures were observed in group FT. CONCLUSION: Intact teeth and the teeth restored with composite and quartz fiber posts had a similar fracture resistance and the failure modes were mostly restorable. The lowest fracture resistance and the most non-restorable failures were observed in conjunction with metal posts. CLINICAL SIGNIFICANCE: The results of this in vitro study suggest the use of a quartz fiber post used in conjunction with an MOD composite resin restoration improves fracture resistance in an endodontically treated premolar.