Evaluation of the Mechanical and Adhesion Characteristics of Indirect Restorations Manufactured with Three-Dimensional Printing.

The aim of this study was to investigate the marginal fit and bond strength characteristics of onlay restorations manufactured by three-dimensional printing (Varseo XS, Bego GmbH, Bremen, Germany) and CAD/CAM (CAMcube, Montreal, QC, Canada) systems. Class II onlay cavities on sixty mandibular molars were prepared in cavities and restored in three separate groups using different fabrication methods. Digital and conventional impressions were taken to design the restorations in the CAD system (DWOS, Straumann GmbH, Freiburg, Germany). To evaluate the marginal fit and void volumes, all specimens were scanned with microcomputed tomography. A microshear test was performed to compare the bond strength of the restorations to the tooth surface. The marginal fit values measured for the 3D-printed and CAD/CAM onlay restorations were found to be at clinically acceptable levels (<120 µm), and no significant difference could be observed between the three different fabrication methods (p > 0.05). According to the microshear test results, the CAD/CAM group had the highest bond strength values before (34.82 MPa) and after (26.87 MPa) thermal cycling (p < 0.05), while the 3D-printed and conventionally produced onlays had similar results (p < 0.05). 3D printing technology is a promising option for indirect restorations; however, the post-production phase is as crucial as the printing and cementation phases.

The effect of different energy levels of the Er: YAG laser on the repair bond strength of a nanohybrid composite resin.

This study evaluates the durability of repair microshear bond strength (µSBS) of nanohybrid composite resins which surfaces are treated with different laser parameters and bur. A total of 240 nanohybrid composite resin disk shaped specimens were prepared. Then, specimens were divided into eight test groups as regards to surface treatment types (Erbium (Er:YAG) laser with seven different parameters and bur). Half of the specimens in each group were subjected to 5000 thermal cycling (TC) and the other half to 20,000 TC. Universal testing machine was used for µSBS test. The data were analyzed with a two-way analysis of variance and Tukey test. Among the specimens treated with ER:YAG laser+5000 TC, we detected the highest mean µSBS test values in the subgroups L200 and L250. Among the specimens treated with ER:YAG laser+20,000 TC, the highest mean µSBS test values were seen in the L200 subgroup. The µSBS values after the 20,000 TC were significantly lower than those after 5000 TC for all different treatment types. Thermal cycling and laser energy levels have effects on repair µSBS. Considering the bond strength and durability it seems more effective to use Er:YAG laser at 200 mJ. To repair an aged nanohybrid composite resin, Er:YAG laser surface treatments may provide some benefits by acquiring a reliable bond strength with durability. This study may give information on which parameters are more suitable to use Er:YAG laser for the repair of nanohybrid composite resins.

The Effect of Flowable Composite Resins on Periodontal Health, Cytokine Levels, and Immunoglobulins.

Objective: This study investigated the effects of flowable resin composites (FCR) on the restoration of noncarious cervical lesions (NCCL) and their impact on periodontal tissues. Materials and Methods: 30 periodontally healthy patients were assigned into three groups randomly; group VF: self-adhering FCR, group NF: fluoride-releasing FCR, and group SF: microhybrid FCR. Gingival crevicular fluid (GCF) volume levels of osteoprotegerin (OPG), immunoglobulins (IgA, IgM), and interleukins (IL-1, IL-1ß, and IL-10) in GCF were analyzed with ELISA tests. Clinical success rates were evaluated using USPHS criteria during the 12-month follow-up. Results: The GCF volume was increased mostly in group SF (1.34 ± 0.09 µl). While the titer of interleukin was increased in all groups, higher increases were observed in IL-1 and IL-1ß in group NF (170.78 pg/ml and 39.35 pg/ml). Increased IL-10 was observed in group VF (14.33 ± 0.85 pg/ml). IgA levels varied partially among all groups (p > 0.05), and even IgM levels were elevated immediately after the restoration process but returned to normal on the 28th day (p < 0.05). Group NF failed in most of the USPHS criteria, while the material group VF and group SF presented acceptable results except in the marginal adaptation criterion (p < 0.05). Conclusions: Clinical efficacy of self-adhering FCR was found the best for restoration of NCCL while fluoride-releasing FCR stimulated the periodontal response and had negative effects on GCF volume, cytokine, and immunoglobulin levels.

The effect of composite placement technique on the internal adaptation, gap formation and microshear bond strength.

Purpose: This study aimed to compare the efficiency of placement technique on internal adaptation, gap formation and microshear bond strength (SBS) of bulk-fill composite resin materials. Materials and methods: Standardized class V cavities were prepared for microcomputed tomography (mCT) test and divided into four groups (n=12) as follows: Group SDR: Smart Dentin Replacement system/bulk fill; Group SF2: Sonic-Fill system/bulk fill sonic-activated composite placement system; Group CHU: Herculite-XRV-Ultra composite resin inserted with Compothixo/sonic-vibrated composite resin placement system; Group HIT: Herculite-XRV-Ultra composite resin applied with incremental technique. Self-etch adhesive (Optibond-XTR) was used for bonding in all groups. After 10000 thermocycling, mCT scans were taken to reveal gap formation at the toothrestoration interface and universal testing machine was used to test microshear bond strength SBS values (n=10). ANOVA, post-hoc Bonferroni and Tukey HSD tests were used for evaluating the gap formation and SBS values p=0.05. Results: SF2 and CHU showed the best adaptability compared with both SDR and HIT. The difference between groups SDR and HIT was statistically significant (p<0.05).SBS values were found to be the highest for SF2, and the lowest for HIT groups (p>0.05). Conclusion: Bulk-fill composite resins placed either with sonic-activated or sonic-vibrated instrument demonstrated better adaptability, less gap formation and higher bond strength than both the bulk-fill flowable composite and conventional incremental techniques.

Finite element analysis and nanomechanical properties of composite and ceramic dental onlays.

The aim is to evaluate the mechanical properties of the composite and ceramic based indirect restorative materials used in dental treatments with scanning nanoindentation test (NT). Finite element analysis (FEA) was applied to investigate the stress distribution. Four hybrid composite materials; Indirect resin composite (IRC), Resin nanoceramic (RNC), Polymer infiltrated ceramic (PIC) and Zirconia-reinforced lithium-di-silicate (ZRC) were divided into two subgroups for NT (n = 20) and fracture test (n = 40). Statistical analyses were performed with independent t-test, ANOVA and post-hoc Tukey tests (p ≤ 0.05). The highest hardness, elasticity and fracture toughness were observed in ZRC (p = 0.001). Frequency of vertical root fractures in RNC and IRC were statistically lower than ZRC (p = 0.032). Reinforced CAD-CAM ceramics revealed higher mechanical properties compared with IRC materials. The FEA model for fracture mechanism of RNC demonstrated lowest stress values and uniform stress distribution amongst all groups, while ZRC and PIC presented the highest fracture toughness.

Efficacy of different calcium silicate materials as pulp-capping agents: Randomized clinical trial.

BACKGROUND/PURPOSE: Calcium hydroxide-based materials were the gold standard in vital pulp therapies for decades' despite of several shortcomings. However, calcium silicates have been discussed as an alternative to overcome these drawbacks. It was aimed to investigate the in-vivo effectiveness of different calcium silicates based materials in pulp capping in this study. MATERIALS AND METHODS: A parallel-design, randomized controlled trial with 213 patients who has deep dentin caries, vital pulps and without spontaneous pain or history of swelling was designed. 525 M teeth were randomized, blinded and allocated to one of the five groups for pulp capping treatment (n = 105). All teeth were followed up clinically and radiographically (after 1st, 6th, 12th and 36th months) by blinded investigators. The clinical and radiographic success, and the effect of the pulp exposure to the success rate analyzed with Wald chi-square and Z tests. RESULTS: Clinical and radiographic success of MTA+ (86.3%, 85.4%) and Biodentine (79.4%, 80.1%) were found the highest. Although results of Theracal LC group (72.1%, 73.6%) were better than Dycal group (69.4%, 70.2%), the difference was nonsignificant (p > 0.05). Only in light-cured groups, (TheraCal LC & LC Calcihyd) pulpal exposure size effected the success of the materials (p < 0.05). MTA+ and Biodentine resulted better scores, when compared with TheraCal LC in large pulpal exposures (p < 0.05). CONCLUSION: After 36-month follow-up, both MTA+ and Biodentine were found to be the appropriate material for direct pulp capping in permanent teeth. The filler ingredient of the Theracal-LC eases the usage of calcium silicates but decreases the success rate.

Evaluation of the relationship between migraine disorder andoral comorbidities: multicenter randomized clinical trial.

BACKGROUND/AIM: Although migraine is a common disorder, there is a lack of research investigating the possible relationship between migraine and oral health. The aim of the present study was to explore the relationship between temporomandibular disorders, bruxism, dental caries, periodontal status, and migraine disorder in a multicenter, parallel, case-controlled clinical study. MATERIALS AND METHODS: A total of 2001 participants were divided into two groups: migraineurs (nm = 998) and nonmigraineurs (nh = 1003). International Headache Society's Second Edition of International Classification of Headache Disorders and modified Migraine Disability Assessment surveys were administered to evaluate the level of migraine; a pretreatment questionnaire and the World Health Organization oral health assessment form were used to determine the oral comorbidities and their possible effects on DMFT index, gingival plaque index, existence of temporomandibular disorders, bruxism, and consistency of daily oral hygiene habits. RESULTS: The mean age was 39.6 ± 10.5 years. Female patients seemed to experience migraine attacks more than male patients (64%). The frequency of gastroesophageal reflux was higher in migraineurs in comparison with nonmigraineurs (47%) and tooth wear and abrasion also seemed more frequent (76%). DMFT and plaque index scores showed significant differences for both groups. CONCLUSION: There is a strong relationship between migraine and oral health status. The existence of reflux in addition to migraine leads to higher dental problems.

Comparative clinical evaluation of the efficacy of a new method for caries diagnosis and excavation.

AIM: The purpose of this study is to compare the efficiency of fluorescence-aided caries excavation (FACE) to remove carious dentin primary teeth with that of conventional methods. METHODS AND MATERIALS: After caries excavation was carried out, dentin surfaces were conventionally inspected using visual tactile criteria and 415 cavities which were classified as caries-free, re-inspected with Face-Light and caries detector dye (CDD) methods. Orange-red fluorescing areas classified as carious dentin, as well as stained carious dentin. All the data were recorded according to localization of the caries and determination efficiency of the methods. X(2) test was used to compare the mean values of both Face-Light and dye applications, while Wilcoxon test performed to evaluate the effectiveness for each diagnostic method. RESULTS: A total of 273 patients with 415 Class II (OM/OD) cavities (1.65 ± 0.52 teeth per patient) with carious lesions in molar and premolar teeth, were examined. Out of 415 teeth, in 149 teeth (35.9%) no caries findings had been illustrated. While FACE detected remaining carious or partially removed areas in 237 teeth (57.2%), CDD stained only 29 teeth by itself (P < 0.05). CONCLUSION: In conclusion, FACE has a higher detectability compared to visual inspection and caries detector dye in diagnosis and removal of carious dentin.

Spectrophotometric and computerized evaluation of tooth bleaching employing 10 different home-bleaching procedures: In-vitro study.

OBJECTIVE: The aim of this in-vitro study was to evaluate the efficacy of bleaching products, determine the applicability and validation of the measurement methods. MATERIALS AND METHODS: Freshly extracted 110 human incisor teeth were stained with whole blood and hemolysate solution prior to the application of 10 different home-bleaching products. Spectrophotometric measurements of the tooth shades were performed for each specimen before and after bleaching at the 1(st), 3(rd), 7(th), and 14 days. Differences in lightness (Δl), chroma (Δc), hue (Δh) values and shade changes were measured to evaluate process. Computerized digital imaging analyses to determine the color changes were performed with Photoshop CS4 software (Adobe, San Jose, CA, USA). Statistical analyses were performed with analysis of variance, Scheffe and Tukey tests. RESULTS: In all of the test groups regardless of the material used, a significant increase in lightness and hue, and decrease of chroma were observed, as compared to the control group. After recommended bleaching applications, Δl and Δh values respectively increased in group Zaris White and Brite (ZWB) and group Pola Night and Δc values showed significant decrease in groups ZWB and Rembrandt REM3 (P < 0.05). At the end of the procedure both spectrophotometric and digital imaging analysis showed ZWB was the most effective product among the others while Yotuel and Happy Smile were the least (P < 0.05). CONCLUSIONS: Home-bleaching systems showed slower but almost permanent bleaching effect likewise office-based methods. Both software and spectrophotometric analyses have advantages such as evaluating the results objectively and numerically, also treatment outcomes could be preserved.

Evaluation of the apical adaptation performance of various root canal instruments.

OBJECTIVE: The aim of this study was to evaluate the apical root canal adaptation performance of various root canal instruments. MATERIALS AND METHODS: A total of 40 freshly extracted single-rooted mandibular incisors were used in this study. Coroner parts of all teeth were removed from cemento-enamel junction and root canal of each tooth was explored with a size 8 K-file until the tip of the file was just visible at the apex. Working lengths (WLs) were determined as 1 mm short of these measurements. ProTaper, K-file, profile and hedstroem files were inserted into the root canals of 10 teeth to the WL following the flaring of the coronal and middle thirds. Instruments were fixed in the root canals with acrylic resin. The apical 1 mm of each root tip was ground on wet sandpaper to expose the canal and the instrument at the WL and the apical region of each tooth was examined under stereomicroscope. The stereoscopic images of the teeth were digitized and analyzed with software in order to determine the differences between the areas of root canals and file tips. Result data were analyzed using the one-way analysis of variance test (P = 0.05). RESULTS: There were no significant differences between apical file/root canal areas of the evaluated instruments (P > 0.05). CONCLUSIONS: None of the evaluated instruments performed a perfect adaptation with the apical root canal surface at the WL in mandibular incisors. Therefore, total removal of the debris from the apical canal surface may not be achieved when these filing instruments are used.