A retrospective clinical study on the longevity of posterior Class II cast gold inlays/onlays.

OBJECTIVE: To investigate the longevity and reasons for failure of posterior cast Class II gold inlays and onlays among a group of Norwegian adults. The term inlay was used for both inlays and onlays. METHODS: A cohort of 138 patients regularly attending a general practice for check-up were examined in 2016. The patients had a total of 391 posterior gold inlays placed in the period 1970-2015. The inlays were categorized as successful, repaired or failed. Reasons for failure were classified as either "secondary caries", "fractures", "lost inlay" or "other". Participation was voluntary and no compensation was given. RESULTS: The mean age of the patients at placement was 50.8 years (SD: 12.7 yr). Most gold inlays were placed in molars (85.9%) and 14.1% in premolars; 49.4% of the inlays were in the maxilla and the 50.6% in the mandibula. Average length of follow-up was 11.6 years (range: 1-46 years, SD: 7.9); 82.9% were classified as successful, 10.7% as repaired and 6.4% as failed. Reasons for failure were secondary caries (41.3%), lost inlay (25.4%), fractures (23.8%) and other (9.5%). Mean annual failure rate (AFR) was 1.69% for repaired and failed inlays combined. However, if repaired inlays were considered as success, the AFR decreased to 0.57%. Multi-level Cox regression analyses identified low age of the patient and high number of restored surfaces as risk factors for failure. CONCLUSION: The present retrospective clinical study demonstrated an acceptable annual failure rate for Class II cast gold inlays.

Higher experience of caries and lower income trajectory influence the quality of restorations: A multilevel analysis in a birth cohort.

OBJECTIVES: This study aimed to evaluate the quality of posterior restorations (amalgam or composite) placed in adults from a birth cohort and its association with clinical and socioeconomic determinants experienced during their life course. METHODS: A representative sample (n=539) of all 5914 births occurring in Pelotas (Brazil) in 1982 was prospectively investigated. Quality of posterior restorations (satisfactory or unsatisfactory) was assessed at 31 yrs-old, using modified USPHS criteria. Trained and calibrated dentists performed clinical examination. Explanatory variables included demographic and socioeconomic, oral health and dental service utilization patterns during the life course. Tooth related variables (type of tooth, material, size of cavity) were also analyzed. Untreated caries and socioeconomic status were assessed by group-based trajectories analyses. Multilevel Regression models were used to determine factors associated with restoration outcomes. RESULTS: In total 2123 restorations (53% composite) were evaluated of which 107 (5%) were assessed as failed. The main reasons for failure were tooth/restoration fracture (50.5%) and secondary caries (30.7%). Failures in posterior restorations showed a significant association with socioeconomic aspects (lower tertile of income at age 30 - prevalence ratio (PR) 2.21 [95% CI 1.19-4.09]), clinical variables (trajectory of higher untreated caries - PR 2.11 [95% CI 1.23-3.61]) and also with tooth-related factors (Restorations involving three or more surfaces - PR 5.51 [95% CI 3.30-9.19]) after adjustment for each other. CONCLUSIONS: These findings suggest that, although tooth-related variables have an important role in restoration longevity, patient-related factors, such as socioeconomic variables and untreated caries are also associated with failure and should be taken into account when evaluating longevity of posterior restorations. CLINICAL SIGNIFICANCE: This was the first study assessing long-term trajectory of untreated caries, showing an association between higher experience of caries during the life-course and unsatisfactory restorations. The findings suggest that individual related factors should be considered when planning treatment and in future research evaluating the longevity of dental restorations.

Effect of bulk-fill base material on fracture strength of root-filled teeth restored with laminate resin composite restorations.

OBJECTIVES: To evaluate the effect of using a bulk-fill flowable base material on fracture strength and fracture patterns of root-filled maxillary premolars with MOD preparations restored with laminate restorations. METHODS: Fifty extracted maxillary premolars were selected for the study. Standardized MOD cavities with endodontic treatment were prepared for all teeth, except for intact control. The teeth were divided randomly into five groups (n=10); (Group 1) sound teeth, (Group 2) unrestored teeth; (Group 3) MOD cavities with Vitrebond base and resin-based composite (Ceram. X One Universal); (Group 4) MOD cavities with 2mm GIC base (Fuji IX GP) and resin-based composite (Ceram. X One Universal) open laminate, (Group 5) MOD cavities were restored with 4mm of bulk-fill flowable base material (SDR) and resin-based composite (Ceram. X One Universal). All teeth were thermocycled and subjected to a 45° ramped oblique load in a universal testing machine. Fracture load and fracture patterns were recorded. Data were analyzed using one-way ANOVA and Dunnett's T3 test. RESULTS: Restoration in general increased the fracture strength compared to unrestored teeth. The fracture strength of group 5 (bulk-fill) was significantly higher than the fracture strength of the GIC laminate groups and not significantly different from the intact teeth (355±112N, P=0.118). The type of failure was unfavorable for most of the groups, with the majority being mixed failures. CONCLUSIONS: The use of a bulk-fill flowable base material significantly increased the fracture strength of extracted root-filled teeth with MOD cavities; however it did not improve fracture patterns to more favorable ones. CLINICAL SIGNIFICANCE: Investigating restorative techniques that may improve the longevity of root-filled premolar teeth restored with direct resin restorations.

Posterior composites: Update on cavities and filling techniques.

OBJECTIVES: The aim of this paper is to examine cavity design for posterior resin composite restorations and to discuss various resin composite filling techniques. DATA: Literature with regard to cavity preparation for amalgam and resin composite restorations has been reviewed. An overview of available bulkfill resin composite systems is provided and a categorization of these systems according to their clinical application and their intended use is outlined. SOURCES: A literature search was carried out by the authors in Medline. STUDY SELECTION: Pre-defined inclusion criteria based on keywords were included and reviewed. CONCLUSIONS: Minimum cavity preparations are advised for posterior resin composite restorations, preserving the greatest amount of healthy tooth structure. For resin composite restorations only the lesion of caries needs to be removed with all remaining tooth structure protected for the bonding process. The anticipated outcome of this philosophy will result in increased survival of teeth. Newer bulkfill restorative resins offer many advantages such as reduces time for placement.

Comparative evaluation of microleakage of a carbomer/fluoroapatite-enhanced glass-ionomer cement on primary teeth restorations.

AIM: Carbomer cement represents a novel glass-ionomer which gradually mineralises into fluoroapatite. Purpose of this study was to evaluate microleakage around restorations in deciduous teeth made with composite resin, conventional glass-ionomer cement, resin-modified glass-ionomer cement and carbomer/fluoroapatite-enhanced glass-ionomer cement. MATERIALS AND METHODS: A group of 40 primary upper canines, primary upper and lower molars was divided into 4 groups (n=10). Class I cavities were prepared by diamond cylindrical bur at high speed and were restored with a composite resin (Group 1), with a glass- ionomer cement (Group 2), with a resin-modified glass-ionomer cement (Group 3) and with a carbomer/fluoroapatite-enhanced glass- ionomer cement (Group 4). Hard tissue's bonding involved, in the case of composite resin a total etch bonding procedure, and in glass ionomers the use of their respective primers. Restorations were finished and polished. A 24-hour water storage was followed by thermocycling (1500 cycles, 5°C - 36°C - 55°C - 36°C with a dwell time of 15 seconds) and dye penetration test with immersion in 5% methylene blue for 24 hours. In order to assess the degree of microleakage longitudinal cuts were produced by means of a microtome at 0.5 mm and at 1 mm from the restoration margin, and photographs were taken with a stereomicroscope at 100X. Microleakage was classified according to the number of surfaces and the depth at which dye penetration was observed. Data were analysed with ANOVA and post-hoc analysis was performed with Bonferonni test (p<0.05). RESULTS: Statistical analysis exhibited no significant statistical difference between Group 2 and Group 3 (p>0.05). Statistical difference was exhibited between Group 3 and Group 4 (p<0.01), with Group 4 exhibiting lower microleakage values. Group 1 exhibited the lowest mean microleakage values and statistical difference in comparison with all groups (p<0.001). Group 4 exhibited the lowest microleakage values among the cements. CONCLUSION: Superior marginal integrity is achieved in restored primary teeth when composite resin is used. If the clinical case suggests the use of a glass-ionomer cement, carbomer/fluoroapatite-enhanced glass-ionomer cement is prefered in terms of microleakage.

A comparative microleakage evaluation of three different base materials in Class I cavity in deciduous molars in sandwich technique using dye penetration and dentin surface interface by scanning electron microscope.

INTRODUCTION: A major objective in restorative dentistry is the control of marginal leakage, which may occur because of dimensional changes or lack of adaptation of restorative material to the cavity preparation. Numerous techniques have been advocated to overcome polymerization shrinkage in composite restorations. AIM AND OBJECTIVES: This study investigated microleakage of three different bases under composite resin in sandwich technique using dye penetration and dentin surface interface using scanning electron microscope (SEM). MATERIALS AND METHODS: Sixty extracted deciduous molars were stored in distilled water and Class I cavities with a width of about one-fourth of intercuspal distance and a depth of 0.5-1 mm below the dentino-enamel junction was prepared without bevels. In Group 1 - glass ionomer cement (GIC); Group 2 - mineral trioxide aggregate (MTA); Group 3 - Biodentine™ was placed as a base under composite. Teeth were longitudinally sectioned in two halves, through the centers of the restoration, immersed in 2% methylene blue and microleakage was evaluated under stereomicroscope and surface interface between base and dentin was evaluated under SEM. RESULTS: Under the condition of in vitro study, less microleakage and less internal gaps were seen in Biodentine™ (0.00 ± 0.00 and 4.00 ± 1.59) group than MTA (0.00 ± 0.00 and 6.08 ± 1.82) and GIC (25.25 ± 6.57 and 14.73 ± 3.72, respectively) and showed very strong positive correlation between microleakage and internal gaps. CONCLUSION: Biodentine™ exhibits superior marginal sealing ability as well as marginal adaptation under composite resin as compared to MTA and GIC.

An In-VitroEvaluation of Microleakage at the Cervical Margin Between two Different Class II Restorative Techniques Using Dye Penetration Method.

OBJECTIVE: To evaluate the coronal microleakage of packable composite using conventional incremental and posterior bulk fill flowable composite using Smart Dentine Replacement Single Step technique in the cervical margins of class II cavities in dentine using the dye penetration method. STUDY DESIGN: In-vitroInterventional study. PLACE AND DURATION OF STUDY: Department of Operative Dentistry, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences (DIKIOHS), Karachi, from November 2012 to April 2013. METHODOLOGY: One hundred and twenty extracted teeth (molars and premolars) were collected and randomly divided into two experimental groups (n=60 each) and were stored in normal saline until used. Fractured samples were excluded. Standardized class II proximal box only cavities were prepared and restored with conventional methacrylate based composite using incremental technique (Group A, n=40) and low stress methacrylate resin based composite SDR using single step technique (Group B, n=40). Samples were sectioned horizontally below the cervical margins and specimen disks were prepared. The specimens were thermocycled and sealed with acid resistant varnish leaving a 1-mm interface around cervical margin and immersed in 2% methylene blue buffered solution for 24 hours. Leakage was scored 0 - 4 and measured in mm. It washed and sectioned to evaluate under stereomicroscope. RESULTS: Mean penetration was 2.4280 ±0.79 mm for Group Aand 1.015 ±0.45 mm for Group B (p < 0.001). Maximum dye penetration score for group Awas 4 and group B was 3. CONCLUSION: SDR technique in combination with total etch technique at the cervical margin of class II restorations improved the marginal seal, when were placed in dentine and thermocycled.

Effect of Bulk-filling on the Bonding Efficacy in Occlusal Class I Cavities.

PURPOSE: To evaluate the effect of bulk filling Class I posterior cavities on bonding to cavity-bottom dentin. MATERIALS AND METHODS: Two flowable "base" bulk-fill composites (Filtek Bulk Fill Flowable, SDR), one paste-like "full-body" bulk-fill composite (Tetric EvoCeram Bulk Fill) and one conventional paste-like composite (Filtek Z100) were bonded (G-ænial Bond) to either a flat surface (3.5 x 3.5 x 4 mm; C-factor: 0.18) or a Class I cavity (3.5 x 3.5 x 4 mm; C-factor: 5.8). After 1-week water storage, the restorations were sectioned to obtain 4 rectangular microspecimens that were subjected to microtensile bond strength (µTBS) testing. RESULTS: No significant differences in µTBS were recorded between all composites when bonded onto a flat surface (p > 0.05). When bonded into a Class I cavity, the µTBS of all composites except SDR significantly decreased (p < 0.001). CONCLUSION: Both the configuration factor and the type of bulk-fill composite were found to have a great impact on bonding to cavity-bottom dentin.

Depth and distribution of the cure in a resin-based composite cured in a simulated Class II cavity.

PURPOSE: To examine the effect that a stainless steel (SS) matrix band has on the depth and distribution of cure of a resin-based composite (RBC) in a simulated Class II cavity. METHODS: RBC was cured for 20 seconds in a simulated Class II cavity with and without a SS matrix band, and after 24 hours the specimens were scraped back and ground to expose a vertical central plane where Knoop micro-hardness (KHN) mapping was conducted from 0.05-1.5 mm from the band and in 0.5 mm intervals from the top of the specimens. The effect of different angles of the light guide on the distribution of hardness was also examined. RESULTS: KHN values near the SS matrix band were significantly lower (P < 0.05) than within the bulk of the specimen and were lower than those found without the matrix band. Angles of incidence for the curing light-guide produced changes in the distribution of KHN within the specimens, but particularly near the matrix band, and with a 35° angle of incidence, the depth of cure was significantly different from that of normal incidence of the light.

Evaluation of Microleakage of Nanoionomer and Nanocomposite Restorations, immersed in Fruit Drink, Fresh Fruit Juice and Soft Drink--An in vitro Study.

AIM: To evaluate microleakage of Nanoionomer (3M ESPE Ketac(™) N100 Light cured Nanoionomer Restorative) and Nanocomposite (3M ESPE Filtek(™) Z350 XT Universal Restorative) restorations, immersed in fruit drink, fresh fruit juice and soft drink. STUDY DESIGN: Eighty caries free maxillary premolars extracted for orthodontic purpose were used for the study. Class V cavities were prepared and restored with Nanocomposite on buccal surface and Nanoionomer on the palatal surface. The teeth were thermocycled following the restoration. The experimental groups comprised of 72 teeth (3 groups comprising 24 teeth each for fruit drink, fresh fruit juice and soft drink), while remaining 8 formed the control group. Each of experimental group was further divided into three subgroups (low, medium and high immersion). The teeth were finally immersed in Rhodamine B dye, sectioned and evaluated under stereomicroscope. Statistical analyses used were Mann-Whitney test and ANOVA test. RESULTS: The teeth showed statistically significant microleakage as the immersion regime increased. Soft drink group showed highest microleakage followed by fresh fruit juice and fruit drink. Nanocomposite exhibited more microleakage but the comparison was not statistically significant. CONCLUSION: The three beverages used in the study affected the microleakage of both restorative materials significantly. The microleakage scores increased as the frequency of the immersions increased. Soft drink caused highest microleakage followed by fresh fruit juice and fruit drink.

In Vitro Evaluation of Microleakage and Microhardness of Ethanolic Extracts of Propolis in Different Proportions Added to Glass Ionomer Cement.

OBJECTIVE: To evaluate the effect of ethanolic extracts of propolis (EEP) addition in different proportions to glass ionomer cement (GIC) on microleakage and microhardness of GIC. STUDY DESIGN: The cement was divided into four groups: one using the original composition and three with 10%, 25%, and 50% EEP added to the liquid and then manipulated. For microleakage assessment, sixty primary molars were randomly divided into four groups (n=15). Standard Class II cavities were prepared and then filled with EEP in different proportions added to GICs. Microleakage test was performed using a dye penetration method. The data were analyzed using one-way ANOVA and Mann-Whitney U tests (α = 0.05). Disc shaped specimens were prepared from the tested GIC to determine Vickers hardness (VHN). The data were analyzed using one-way ANOVA and post hoc Tukey test (α = 0.05). RESULTS: There were no statistically significant differences between the groups in terms of microleakage (p > 0.05). There were statistically significant differences between the VHN values of groups (p < 0.05). Increasing addition of EEP to GIC statistically significantly increased VHN value of GIC (p < 0.05). CONCLUSIONS: The addition of EEP to GIC increased the microhardness of the GIC and did not adversely affect the microleakage. Thus, it might be used during routine dental practice due to its antibacterial properties.

British Society of Prosthodontics Debate on the Implications of the Minamata Convention on Mercury to Dental Amalgam--Should our Patients be Worried?.

In 2013, the Minamata Convention on Mercury called for a global phase-down of amalgam use, with a view to reduce environmental mercury pollution. This will significantly impact UK dentistry, given the still extensive use of amalgam in U.K. general dental practice. However, until now there has been little national discussion or debate. In Spring 2015, The British Society of Prosthodontics dedicated a significant part of its Annual Conference to debating the implications of this issue. Clinical case examples were discussed with audience interaction and voting facilitated using innovative Audience Response System Technology. A remarkable range of concerns and opinions were given. The debate elicited specific concerns amongst clinicians regarding the suitability of mercury-free alternatives to amalgam; particularly where cavities are large and extend beneath the gingival anatomy. There are also anecdotal reports of Dental Foundation (DF) dentists not being adequately taught the use of dental amalgam in undergraduate dental schools. CPD/CLINICAL RELEVANCE: Many clinicians, especially those treating patients for whom moisture control is challenging, feel that amalgam should remain available for clinicians to choose in certain clinical circumstances for the restoration of posterior teeth, even in the event of a complete phase-down.

Fatigue resistance and crack propensity of novel "super-closed" sandwich composite resin restorations in large MOD defects.

OBJECTIVES: To assess the influence of conventional glass ionomer cement (GIC) vs resin-modified GIC (RMGIC) as a base material for novel, super-closed sandwich restorations (SCSR) and its effect on shrinkage-induced crack propensity and in vitro accelerated fatigue resistance. METHODS: A standardized MOD slottype tooth preparation was applied to 30 extracted maxillary molars (5 mm depth/5 mm buccolingual width). A modified sandwich restoration was used, in which the enamel/dentin bonding agent was applied first (Optibond FL, Kerr), followed by a Ketac Molar (3M ESPE)(group KM, n = 15) or Fuji II LC (GC) (group FJ, n = 15) base, leaving 2 mm for composite resin material (Miris 2, Coltène-Whaledent). Shrinkageinduced enamel cracks were tracked with photography and transillumination. Samples were loaded until fracture or to a maximum of 185,000 cycles under isometric chewing (5 H z), starting with a load of 200 N (5,000 X), followed by stages of 400, 600, 800, 1,000, 1,200, and 1,400 N at a maximum of 30,000 X each. Groups were compared using the life table survival analysis (α = .008, Bonferroni method). RESULTS: Group FJ showed the highest survival rate (40% intact specimens) but did not differ from group KM (20%) or traditional direct restorations (13%, previous data). SCSR generated less shrinkage-induced cracks. Most failures were re-restorable (above the cementoenamel junction [CEJ]). CONCLUSIONS: Inclusion of GIC/RMGIC bases under large direct SCSRs does not affect their fatigue strength but tends to decrease the shrinkage-induced crack propensity. CLINICAL SIGNIFICANCE: The use of GIC/ RMGIC bases and the SCSR is an easy way to minimize polymerization shrinkage stress in large MOD defects without weakening the restoration.

Effective Expansion: Balance between Shrinkage and Hygroscopic Expansion.

The purpose of this study was to investigate the relationship between hygroscopic expansion and polymerization shrinkage for compensation of polymerization shrinkage stresses in a restored tooth. One resin-modified glass-ionomer (RMGI) (Ketac Nano, 3M ESPE), 2 compomers (Dyract, Dentsply; Compoglass, Ivoclar), and a universal resin-based composite (Esthet•X HD, Dentsply) were tested. Volumetric change after polymerization ("total shrinkage") and during 4 wk of water storage at 37°C was measured using an optical method (n= 10). Post-gel shrinkage was measured during polymerization using a strain gauge method (n= 10). Extracted human molars with large mesio-occluso-distal slot preparations were restored with the tested restorative materials. Tooth surfaces at baseline (preparation), after restoration, and during 4 wk of 37°C water storage were scanned with an optical scanner to determine cuspal flexure (n= 8). Occlusal interface integrity was measured using dye penetration. Data were analyzed using analysis of variance and post hoc tests (significance level 0.05). All tested materials shrunk after polymerization. RMGI had the highest total shrinkage (4.65%) but lowest post-gel shrinkage (0.35%). Shrinkage values dropped significantly during storage in water but had not completely compensated polymerization shrinkage after 4 wk. All restored teeth initially exhibited inward (negative) cuspal flexure due to polymerization shrinkage. Cuspal flexure with the RMGI restoration was significantly less (-6.4 µm) than with the other materials (-12.1 to -14.1 µm). After 1 d, cuspal flexure reversed to +5.0 µm cuspal expansion with the RMGI and increased to +9.3 µm at 4 wk. After 4 wk, hygroscopic expansion compensated cuspal flexure in a compomer (Compoglass) and reduced flexure with Dyract and resin-based composite. Marginal integrity (93.7% intact restoration wall) was best for the Compoglass restorations and lowest (73.1%) for the RMGI restorations. Hygroscopic expansion was more effective in compensating shrinkage stress than would be assumed based on total shrinkage, because only post-gel shrinkage needed compensation. Effective expansion is therefore hygroscopic expansion minus post-gel shrinkage.

Clinical Evaluation of Indirect Composite Resin Restorations Cemented with Different Resin Cements.

PURPOSE: To clinically evaluate the performance of indirect composite resin restorations cemented with conventional and self-adhesive resin cements over a 12-month period. MATERIALS AND METHODS: Ten patients fulfilled all the inclusion criteria. Twenty-four composite resin restorations were performed using an indirect technique and cemented with a resin cement (RelyX ARC) or a self-adhesive resin cement (RelyX U100). Two independent evaluators analyzed the restorations using modified USPHS criteria after periods of two weeks and 6 and 12 months. Statistical significance between the cements at each timepoint was evaluated with the Wilcoxon test and between timepoints with the Mann-Whitney test, both at a significance level of 5%. Fisher's exact test was used to assess the occurrence of absolute failures. RESULTS: No statistically significant differences were found between the groups at the same timepoint nor between groups at different timepoints. The only significant difference was found for color match for both groups after 12 months. CONCLUSION: After 12 months, indirect composite resin restorations cemented with self-adhesive resin cement performed similarly to those cemented with conventional resin cement.

Influence of Cavity Margin Design and Restorative Material on Marginal Quality and Seal of Extended Class II Resin Composite Restorations In Vitro.

PURPOSE: To investigate the influence of three cavity designs on the marginal seal of large Class II cavities restored with low-shrinkage resin composite limited to the enamel. MATERIALS AND METHODS: One hundred twenty (120) intact human molars were randomly divided into 12 groups, with three different cavity designs: 1. undermined enamel, 2. box-shaped, and 3. proximal bevel. The teeth were restored with 1. an extra-low shrinkage (ELS) composite free of diluent monomers, 2. microhybrid composite (Herculite XRV), 3. nanohybrid composite (Filtek Supreme XTE), and 4. silorane-based composite (Filtek Silorane). After artificial aging by thermocycling and storage in physiological saline, epoxy resin replicas were prepared. To determine the integrity of the restorations' approximal margins, two methods were sequentially employed: 1. replicas were made of the 120 specimens and examined using SEM, and 2. the same 120 specimens were immersed in AgNO3 solution, and the dye penetration depth was observed with a light microscope. Statistical analysis was performed using the Kruskal-Wallis and the Dunn-Bonferroni tests. RESULTS: After bevel preparation, SEM observations showed that restorations did not exhibit a higher percentage of continuous margin (SEM-analysis; p>0.05), but more leakage was found than with the other cavity designs (p<0.05). The lowest percentage of continuous margin was observed in ELS restorations (p<0.05). More fractured margins were observed in the undermined enamel cavity design groups (p<0.05). CONCLUSION: Bevel preparation failed to improve margin quality in large Class II composite restorations and is no longer recommended. However, undermined enamel should be removed to prevent enamel fractures.

A study on the survival of primary molars with intact and with defective restorations.

BACKGROUND: Failed restorations in primary teeth are not always re-restored. Is re-restoration not required anymore? OBJECTIVE: To compare survival rates of primary molars with intact and defective amalgam and ART restorations. METHODS: A total of 649 restored primary molars, of which 162 were assessed with defective restorations for mechanical reasons, from a cluster-randomised controlled clinical trial, were followed up over a period of 3.5 years. Restored primary molars, extracted because of dental sepsis or toothache, were considered a failure. Primary molars with defective restorations were followed up from the time they were assessed defective. Data were analysed using PHREG model with frailty correction, Wald test, t-test, and jackknife procedure. RESULTS: The survival rate of primary molars with intact restorations (96.3%) was statistically significantly higher than that of primary molars with defective restorations (75.9%) over a 3-year period (P < 0.0001). Neither the effect of treatment protocol (amalgam or ART) (P = 0.05) nor the type of surface (single or multiple) (P = 0.73) was observed with respect to the survival rate of restored primary molars. CONCLUSIONS: Survival rates for primary molars with intact and defective amalgam and ART restorations were high. The 3-year survival rate of primary molars with intact restorations was significantly higher than that of primary molars with defective restorations.

Evaluation of a novel repetitive gas-enhanced permeation test for restoration leakage determination after thermo-mechanical loading.

OBJECTIVES: To assess leakage of class-I restorations using a gas-enhanced permeation test (GEPT) as compared with conventional SEM or dye analysis. MATERIALS AND METHODS: Pressure differences over time and penetrating water volumes were measured simultaneously in a two-chamber system (GEPT) before and after class I cavity preparation in 30 molars. Ten teeth were restored with a composite restoration without bonding (A1), a composite restoration with bonding (A2) or a ceramic indirect restoration (B). Five intact teeth served as controls (C). Another GEPT measurement was performed and impressions were taken. Teeth were subjected to thermodynamic loading (1 200 000 cycles) and final GEPT measurements and impressions were made. SEM evaluation of the marginal continuity was performed and teeth were subjected to a Fuchsin dye penetration test. Spearman's rank test was used to compare results from different tests. RESULTS: The GEPT and SEM values did not correlate before loading (0.359, p = 0.051), but significantly correlated afterwards (0.662, p < 0.0001). The correlations between the Fuchsin dye penetration test and GEPT and SEM surface marginal analysis were significant (0.777 and 0.534, p-values < 0.0001 and 0.002, respectively). CONCLUSIONS: SEM marginal analysis was mainly limited in reflecting the surface restoration integrity. GEPT evaluation may, therefore, serve as a tool to non-destructively assess restoration sub-surface integrity over time. CLINICAL RELEVANCE: The current study provided proof that restoration margin quality does not necessarily reflect its leakage behaviour.