Variations in maxillary second molar position of untreated subjects with normal occlusions: A long-term observational study.

INTRODUCTION: The purpose of the present study was to evaluate the long-term variations in maxillary second molar position in untreated subjects with normal occlusion. SETTING AND SAMPLE POPULATION: A sample of 39 subjects (18 females and 21 males) selected from the University of Michigan Growth Study (UMGS) was followed longitudinally with digital dental casts at 3 observation times: T1, when the maxillary permanent second molars were fully erupted, T2, last observation available in the longitudinal series (38 subjects), and T3, at least 20 years after T2 (12 subjects). MATERIALS AND METHODS: Digital measurements were recorded with an open-source software. Outcome variables were sagittal and transverse inclinations of the upper second molars. Two mixed-effect models were performed. RESULTS: The maxillary second molars had a distolingual inclination at T1, T2 and T3. Sagittal and transverse inclination showed progressive significant uprighting from T1 through T3 (P < .001). From T1 to T2, the adjusted difference in sagittal crown inclination was 8.0° (95% CI from 6.5° to 9.6°; P < .001). From T2 to T3, the adjusted difference was 5.5° (95% CI from 3.0° to 8.1°; P < .001). From T1 to T2, the adjusted difference in transverse crown inclination was 1.9° (95% CI from 0.4° to 3.5°; P = .011). From T2 to T3, the adjusted difference was 6.0° (95% CI from 3.4° to 8.5°; P < .001). CONCLUSIONS: Along with age, maxillary second molars showed a progressive significant uprighting with a decrease in the distal and lingual inclinations.

Color stability of resin-based composites: Staining procedures with liquids-A narrative review.

OBJECTIVE: The objective of this study was to review the experimental staining procedures performed in in-vitro studies for evaluating color stability of resin-based composites used for direct restorations. OVERVIEW: A review was performed with the purpose to identify in vitro procedures carried out to establish staining and color stability of resin-based composites used for direct restorations. A literature search was performed on four online databases (PubMed, Scopus, Embase and Web of Science) for articles published from January 1st 2001 till March 20th 2021, using a combination of free words and Medical Subject Headings (MESH) terms: "Composite Resins" AND "Color Stability" OR "Staining." Two reviewers screened titles and/or abstracts of 1728 unique studies. In total, 208 studies were selected for full-text reading, from which 178 were included in the review. The assessed variables were specimen dimensions, shape, and surface finishing; time before immersion; staining media type, dwell time, temperature and renewal interval; type of composite; color and translucency assessment parameters and measuring system. One hundred and seventy-eight articles analyzed color stability with staining liquids. Coffee was the most used staining medium (n = 102), followed by tea (n = 61), and red wine (n = 55). A disc-shaped specimen was used in most studies (n = 170) with a 2 mm thickness (n = 116). Spectrophotometers were the most used color assessment devices (n = 154), followed by colorimeters (n = 17). Color differences were quantified with ΔE (n = 154), ΔE00 (n = 23). Acceptability and or perceptibility thresholds were also taken into consideration (n = 126). CONCLUSIONS: The large variety of staining procedure suggests the need for standardization. CLINICAL SIGNIFICANCE: Aesthetic failure due to discoloration is a relevant clinical problem. Evaluating benefits and drawbacks of resin based composites artificial staining procedures will improve to predict materials clinical performances.

Flexural resistance of CAD-CAM blocks. Part 3: Polymer-based restorative materials for permanent restorations.

PURPOSE: Concurrently with the growing interest in CAD-CAM systems, several new materials of different chemical nature have become available. As an alternative to ceramics, numerous polymer-based materials have recently been proposed for permanent prosthetic restorations. Aim of this study was to test the CAD-CAM polymer-based materials available on the market, comparing mean flexural strength, Weibull characteristic strength and Weibull modulus. METHODS: Seven types of polymer-based blocks were tested: Lava Ultimate, 3M; Brilliant Crios, Coltene; Cerasmart, GC; Block HC, Shofu; Katana Avencia, Noritake; Grandio Blocs, Voco; Tetric CAD, and Ivoclar-Vivadent. Specimens were cut out from blocks, finished, polished, and tested in a three-point bending test apparatus until failure (n=30). Flexural strength, Weibull characteristic strength, and Weibull modulus were calculated. Flexural strength data were statistically analyzed. ANOVA on Ranks was applied, followed by the Dunn's test for post hoc comparisons (P= 0.05). RESULTS: Flexural strength values (MPa) were measured (mean±standard deviation). Different letters in parentheses label statistically significant differences: Grandio Blocs 266±24(a), Brilliant Crios 259±21(ab); Tetric CAD 254±15(ab); Katana Avencia 241±29(bc); Cerasmart 221±24(cd); Lava Ultimate 196±23(de); Block HC 139±10(e). All the tested materials had flexural strengths greater than 100 MPa, thereby satisfying the requirements of ISO standards for polymer-based materials. For all the tested materials the Weibull characteristic strength was greater than 100 MPa. Weibull modulus ranged between 21.20 (Tetric CAD) and 9.09 (Katana Avencia). CLINICAL SIGNIFICANCE: Even though all the CAD-CAM polymer-based materials marketed in blocks tested in the present study satisfy the requirements of ISO standard for polymer-based materials, their flexural resistance differs significantly. The data presented in the study may be helpful to clinicians for selecting the most appropriate materials for each clinical case.

A pilot trial on lithium disilicate partial crowns using a novel prosthodontic functional index for teeth (FIT).

BACKGROUND: Lithium disilicate is now a well accepted material for indirect restorations. The aim of this trial was to evaluate two lithium disilicate systems using a novel prosthodontic Functional Index for Teeth (FIT). METHODS: Partial adhesive crowns on natural abutment posterior teeth were made on sixty patients. Patients were divided into two groups: Group 1 IPS e.max press (Ivoclar-Vivadent, Schaan, Liecthestein), and Group 2 Initial LiSi press (GC Co., Tokyo, Japan). The restorations were followed-up for 3 years, and the FIT evaluation was performed at last recall. The FIT is composed of seven variables (Interproximal, Occlusion, Design, Mucosa, Bone, Biology and Margins), each of them are evaluated using a 0-1-2 scoring scheme, and is investigated by an oral radiograph and occlusal and buccal pictures. More in details, three variables have the three scores made on the presence or not of major, minor or no discrepancy (for 'Interproximal', 'Occlusion' and 'Design'), presence or not of keratinized and attached gingiva ('Mucosa'), presence of bone loss > 1.5 mm, < 1.5 mm or not detectable ('Bone'), presence or not of Bleeding on Probing and or Plaque Index ('Biology'), presence of detectable gap and marginal stain or not ('Margins'). The Mann-Whitney 'U' test was used and the level of significance was set at p < 0.05. Also, "success" of the crowns (restoration in place without any biological or technical complication) and "survival" (restoration still in place with biological or technical complication) were evaluated. RESULTS: Regarding FIT scores, all partial crowns showed a stable level of the alveolar crest without detectable signs of bone loss in the radiographic analysis. All other evaluated parameters showed a high score, between 1.73 and 2. No statistically significant difference emerged between the two groups in any of the assessed variables (p > 0.05). All FIT scores were compatible with the outcome of clinical success and no one restoration was replaced or repaired and the success rate was 100%. CONCLUSIONS: The results showed that it is possible to evaluate the clinical performance of partial crowns using FIT. The FIT proved to be an effective tool to monitor the performance of the restorations and their compatibility with periodontal tissues at the recall. The FIT can be really helpful for a standardized evaluation of the quality of the therapy in prosthodontic dentistry. The two lithium disilicate materials showed similar results after 3 years of clinical service. TRIAL REGISTRATION: The study protocol was approved by the Ethical Committee of University of Siena (clinicaltrial.gov # NCT01835821), 'retrospectively registered'.

Rhinofibroscopic and Rhinomanometric Evaluation of Patients with Maxillary Contraction Treated with Rapid Maxillary Expansion. A Prospective Pilot Study.

OBJECTIVE: The aim of this study was to evaluate through nasal fiber optic endoscopy and rhinomanometry the patency of upper nasal airways in patients treated with rapid palatal expansion Study design: 30 patients (12 males and 18 females) aged 7-11 years with transverse maxillary constriction underwent rhinomanometric and fiberoptic examination before (T0) and after rapid palatal expansion (T1).The amount of nasopharynx obstruction was quantified with reference to the full choanal surface. Nasal resistance was recorded separately for right and left sides, and combined for both sides. The differences in nasopharynx obstruction and in nasal resistance between T0 and T1 were statistically evaluated. RESULTS: The amount of nasopharynx obstruction significantly decreased after palatal expansion (p<0.001). Total nasal inspiration and expiration resistance significantly decreased at T1 (p<0.001). The reduction ranged between 0. 23 and 0. 66 Pa/cm3/s for inspiration and between 0. 20 and 0,.58 Pa/cm3/s for expiration. A statistically significant positive correlation existed between the T1-T0 differences in the amount of nasopharynx obstruction and the T1-T0 differences in expiration nasal airway resistance (Spearman's correlation coefficient rho = 0.38; p = 0.03). CONCLUSIONS: Rapid maxillary expansion has an influence on nasal resistance and improves the patency of upper airways in patients with minor or moderate breathing problems.

Lateral approach for sinus floor elevation: large versus small bone window - a split-mouth randomized clinical trial.

OBJECTIVES: To test whether a reduction of bone window dimension, in a split-mouth randomized study design, focused on lateral sinus floor elevations, can achieve better results than a wider window in terms of augmented bone height and a reduction of patient discomfort and surgical complications. MATERIALS AND METHODS: Of the sixteen subjects enrolled in the study, each underwent a bilateral sinus lift procedure based on two different access flaps to maxillary sinus. Test side: small access window (6 × 6 mm) + bone filling using a special device. Control side: large access window (10 × 8 mm) + manual bone filling. Alveolar bone height and width were measured at pre-op and 6-month post-op CT scans; repeatable measurements were obtained using radiographic stents. Surgical intervention duration was also recorded. Patients' evaluation of surgical discomfort was assessed using a VAS diagram at 7-day, 14-day and 30-day follow-up. RESULTS: A significant bone augmentation in height and width of alveolar crest was obtained in both test (8.71 ± 1.11 mm, 4.70 ± 0.58 mm) and control (8.5 ± 2.02 mm, 4.68 ± 0.70 mm) sides, although no significant differences were found between the two groups. Neither any significant differences emerge in data concerning the duration of the intervention (Test 42.62 ± 6.67 min, Control 41.68 ± 8.34 min). Patients' opinion relating to surgical discomfort showed a preference for test procedure at 7-day, 14-day and 30-day follow-up. CONCLUSIONS: A reduction of window dimensions did not affect the safety of the surgical procedure. The two testing techniques showed no statistically significant differences in surgical intervention duration. Patients' opinion at 7-day and 14-day post-op showed a preference for test procedure.

Performance of CAD/CAM fabricated fiber posts in oval-shaped root canals: An in vitro study.

PURPOSE: To assess the push-out strength, the cement layer thickness and the interfacial nanoleakage of prefabricated fiber posts, CAD/CAM fiber posts and metal cast posts cemented into oval-shaped root canals. METHODS: Oval-shaped post spaces were prepared in 30 single-rooted premolars. Roots were randomly assigned to three groups (n=10), according to the post type to be inserted: Group 1: Prefabricated fiber post (D.T. Light-Post X-RO Illusion); Group 2: Cast metal post; Group 3: CAD/CAM-fabricated fiber post (experimental fiber blocks). In Group 3, post spaces were sprayed with scan powder (VITA), scanned with an inEos 4.2 scanner, and fiber posts were milled using an inLab MC XL CAD/CAM milling unit. All posts were cemented using Gradia Core dual-cure resin cement in combination with Gradia core self-etching bond (GC). After 24 hours, the specimens were sectioned perpendicular to the long axis into six 1 mm-thick sections, which were differentiated by the root level. Sections from six roots per group were used to measure the cement thickness and subsequently for the thin-slice push-out test, whereas the sections from the remaining four teeth were assigned to interfacial nanoleakage test. The cement thickness around the posts was measured in micrometers (µm) on the digital images acquired with a digital microscope using the Digimizer software. Thin-slice push-out test was conducted using a universal testing machine at the crosshead speed of 0.5 mm/minute and the bond strength was expressed in megaPascals (MPa). The interfacial nanoleakage was observed under light microscope and quantified by scoring the depth of silver nitrate penetration along the post-cement-dentin interfaces. The obtained results were statistically analyzed by Kruskal-Wallis ANOVA, followed by the Dunn's Multiple Range test for post hoc comparisons. The level of significance was set at P< 0.05. RESULTS: Statistically significant differences were found among the groups in push-out bond strength, cement thickness and interfacial nanoleakage (P< 0.05). CAD/CAM-fabricated fiber posts achieved retention that was comparable to that of cast metal posts and significantly higher than that of prefabricated fiber posts. The cement layer thickness around CAD/CAM-fabricated fiber posts was significantly lower than around prefabricated fiber posts, but higher than that around cast metal posts. Root level was not a significant factor for push-out strength in any of the groups, whereas it significantly affected cement layer thickness only in the prefabricated fiber post group. No differences were observed in interfacial nanoleakage between CAD/CAM fabricated and prefabricated fiber posts, while nanoleakage recorded in cast metal posts was significantly lower. CLINICAL SIGNIFICANCE: CAD/CAM fabricated fiber posts could represent a valid alternative to traditionally used posts in the restoration of endodontically-treated teeth with oval or wide root canals, offering the advantages of better esthetics, retention, and cement thickness values that are comparable to cast post and cores.

Accuracy, reliability, and efficiency of intraoral scanners for full-arch impressions: a systematic review of the clinical evidence.

OBJECTIVES: The interest on intraoral scanners for digital impressions has been growing and new devices are continuously introduced on the market. It is timely to verify whether the several scanners proposed for full-arch digital impressions have been tested under clinical conditions for validity, repeatability, reproducibility, as well as for time efficiency, and patient acceptance. SEARCH METHODS: An electronic search of the literature was conducted through PubMed, Scopus, Cochrane Library, Web of Science, and Embase, entering the query terms 'digital impression', 'intraoral digital impression', 'intraoral scanning', 'intraoral scanner', 'intraoral digital scanner', combined by the Boolean operator 'OR'. No language or time limitation was applied. SELECTION CRITERIA: Only studies where digital full-arch impressions had been recorded intraorally were considered. RESULTS: In only eight studies full-arch scans had been performed intraorally. Only four studies reported data on validity, repeatability, reproducibility of digital measurements and their samples were limited to subjects in complete permanent dentition. Only two intraoral scanners, Lava COS and iTero, were tested. Scanning times were measured in six studies and varied largely. Patients' acceptance of intraoral scanning was evaluated in four studies, but it was not specifically assessed for children. CONCLUSIONS: The scientific evidence so far collected on intraoral scanning is neither exhaustive, nor up-to-date. Data from full-arch scans performed in children should be collected. For a meaningful assessment of time efficiency, agreement should be reached on the procedural steps to be included in the computation of scanning time.

Influence of luting agent translucency on fiber post retention.

The aim was to assess the influence of cement translucency on the retentive strength of luted fiber posts. Twenty extracted human premolars were randomly divided into four equal groups, based on the combinations of materials to be tested. Two post types of the same size, shape, and chemical composition, but different light-transmission properties [Translucent post (TP) and Opaque post (OP)] were selected. The two post types were luted using the etch-and-rinse, light-curing adhesive in combination with two shades of the same resin cement of markedly different light-transmitting ability [Transparent shade (TS) and Opaque shade (OS)]. Early post retention was assessed using the thin-slice push-out test. Post type did not significantly influence post retention; however, cement translucency emerged as a relevant factor in intraradicular cementation, with the TS achieving higher push-out strengths. The between-factor interaction was also statistically significant; specifically, OP-OS yielded significantly lower retentive strengths than all the other groups. Post translucency did not influence post retention, provided that a highly translucent cement was utilized for luting.

Effect of Reciproc endodontic treatment with three different post space preparation instruments on fiber post retention.

PURPOSE: To assess the effect of three different drills used for post space preparation on fiber post retention after Reciproc endodontic treatment. METHODS: 30 human upper incisors were endodontically treated using Reciproc and warm vertical gutta-percha compaction. Teeth were sealed coronally using Fuji VII, then stored in 0.5% T chloramine solution at 4 degrees C. After 1 week, teeth were randomly assigned to three groups (n = 10) that differed for the drill type used for post space preparation: Group 1: Calibrated drill; Group 2: Largo drill; Group 3: MTwo drill. Illusion posts were luted into the root canals using Gradia Core. After 24 hours, posted roots were transversally cut into 1 mm-thick slices for thin-slice post push-out testing. Two slices per apical, middle, and coronal thirds were obtained, resulting in a total of 6 slices per tooth. Thin-slice push-out test was conducted using a universal testing machine. Post push-out strength was measured in MPa. For the fracture analysis, the specimens were observed using a stereomicroscope at x40 magnification and classified as adhesive [between post-cement (P-C) or dentin-cement (D-C) interface], cohesive (within the post or adhesive cement) and mixed (adhesive and cohesive fractures occurred simultaneously). Between-group differences in post retentive strength were statistically analyzed (Kruskal-Wallis ANOVA, Dunn's Multiple Range test, P > 0.05). Differences in push-out strength among root levels within each group (one-way ANOVA or Kruskal-Wallis ANOVA, depending on the normality of data distribution, P> 0.05) and in failure mode distribution were also statistically evaluated (Fisher's Exact Test, P > 0.05). RESULTS: For each group the mean of MPa values was: (1) 10.41 ± 3.56, (2) 10.98 ± 3.96, and (3) 12.11 ± 1.65. Failure mode was distributed as follows: Adhesive: (1) P-C - 23.3%, D-C - 21.7%; (2) P-C - 20%, D-C - 10%; (3) PrC - 46.7%, D-C - 13.3%; Cohesive: (1) 0.0%, (2) 3.3%; (3) 0.0%; Mixed: (1) 55.0%; (2) 66.7%; (3) 40.0%. The statistical analysis revealed the existence of significant between-group differences (P= 0.002). Group 3 measured significantly higher push-out strengths than Groups 1 and 2, which were comparable. Statistically significant between-group differences emerged also in failure mode distribution (P= 0.004). In Group 3 post-cement adhesive failures were significantly more frequent and mixed failures were significantly less frequent than in Group 2. No statistically significant differences emerged among the different root levels of the tested groups (P > 0.05).

Effect of different prosthetic abutments on peri-implant soft tissue. A randomized controlled clinical trial.

PURPOSE: This randomized clinical trial assessed the effect of three different prosthetic abutments (titanium, gold-hue titanium and zirconia) on peri-implant soft tissue 2 years after treatment in partially edentulous subjects. METHODS: Baseline data concerning (1) thickness of the buccal peri-implant soft tissue, (2) soft tissue thickness above the bone crest, (3) depth/length of transmucosal pathway, and (4) periodontal biotype at adjacent teeth were collected. The final sample consisted of 47 subjects (21 males, 26 females) with a total of 97 implants. A two-level (patient, implant) statistical model was applied. RESULTS: At the 2-year clinical observation, recession of the gingival margin was observed only at 13% of implants irrespective of the type of abutment. No significant correlation between periodontal biotype at adjacent teeth and peri-implant biotype was observed. Furthermore, none of the investigated variables at patient level (age, gender, implant type, periodontal biotype) or at implant level (keratinized tissue thickness, probing depth, soft tissue thickness) was identified as a significant predictor of recession. In conclusion, this study pointed out that (1) abutment type was not able to influence peri-implant variables after 2 years, and (2) caution should be used in considering periodontal biotype at patient level as a possible indicator of the future peri-implant biotype.

Short-term clinical performance of zirconia single crowns with different framework designs: 3-year clinical trial.

PURPOSE: The present prospective clinical study evaluated the influence of coping design on the fracture resistance of CAD/CAM zirconia single crowns layered with dedicated ceramics. METHODS: 56 subjects were provided with 90 zirconia single crowns in posterior regions. Tooth preparations were standardized and the abutment teeth were randomly distributed into three groups, according to three different coping designs (flat design, FD; porcelain-fused-to-metal-like crowns, PFM; anatomically-guided, AG). The zirconia cores were produced using a CAD/CAM software and then were hand-layered with dedicated ceramics. All crowns were cemented with a self-adhesive resin luting agent and the patients were recalled for follow-up visits after 1 month, 6 months, 1, 2 and 3 years of clinical service. The function, esthetics and marginal adaptation of the restorations were evaluated. Statistical analyses were performed to evaluate survival and success of the restorations. RESULTS: Success rates of 100% were reported in Group 2 and Group 3 while the percentage was 80% in Group 1. Three chippings were noticed in Group 1 (FD) and two crowns needed to be replaced after 3 years, resulting in a survival rate of 93.3%. Group 2 and Group 3 had significantly higher 3-year success rates than Group 1 (P < 0.05). Based on the present clinical results, the following conclusions were drawn: the porcelain-fused-to-metal-like and the anatomically-guided frameworks for zirconia single crowns performed better clinically than the flat designed cores in posterior regions after 3 years; standardized tooth preparations achieved even thicknesses of the bilayered restorations; the proper support given to the veneering ceramic by the correct design of the zirconia framework could significantly reduce the risk of chipping during function.

3D Printed Materials for Permanent Restorations in Indirect Restorative and Prosthetic Dentistry: A Critical Review of the Literature.

The objective of this study was to review the scientific evidence currently available on 3D printable materials and 3D printing technologies used for the fabrication of permanent restorations, focusing on material properties that are clinically relevant. A literature search was performed on four databases (MEDLINE/PubMed, Scopus, Cochrane Library, Web of Science) for articles published from January 2013 until November 2023, using a combination of free words: (restorative dentistry OR prosthetic dentistry) AND (3D printing OR additive manufacturing OR rapid prototyping) AND materials. Two reviewers screened titles and/or abstracts of 2.468 unique studies. In total, 83 studies were selected for full-text reading, from which 36 were included in the review. The assessed variables were mechanical properties, reporting in most of the cases positive results, dimensional accuracy and fit, reporting conflicting results with a predominance of positive, aesthetic properties, with positive reports but scarcely addressed, and biological properties, almost unexplored in independent studies. Despite numerous studies with positive results in favor, papers with negative outcomes were also retrieved. Aesthetic and biological properties are conversely still mostly unexplored. There remains a lack of conclusive evidence for viable 3D printable restorative and prosthodontic materials for permanent restorations. Research should be strengthened by defining international standards for laboratory testing and, where pre-clinical data are promising, conducting clinical trials.

Shear bond strength to enamel and flexural strength of different fiber-reinforced composites.

PURPOSE: To assess the shear bond strength to unground human enamel (ESBS) and flexural strength (FS) of different reinforcing fibers used in combination with a flowable composite resin. MATERIALS AND METHODS: For ESBS testing, 90 human molars were selected and randomly divided into 9 groups (n = 10) according to the reinforcing fiber to be tested: 1. RTD Quartz Splint additionally impregnated at chairside with Quartz Splint Resin (RTD); 2. RTD Quartz Splint without additional impregnation; 3. Ribbond-THM (Ribbond) impregnated with OptiBond FL Adhesive; 4: Ribbond Triaxial (Ribbond) impregnated with OptiBond FL Adhesive; 5. Connect (Kerr) impregnated with OptiBond FL Adhesive; 6. Construct (Kerr) impregnated with Opti- Bond FL Adhesive; 7. everStick PERIO (Stick Tech); 8. everStick C&B (Stick Tech); 9. nonreinforced composite Premise flowable (Kerr). Cylinders of flowable composite reinforced with the fibers were bonded to the intact buccal surface of the teeth. After 24 h of storage, shear loading was performed until failure occurred. FS was assessed performing three-point bending test according to ISO Standard 4049/2000. ESBS and FS data were analyzed using one-way ANOVA, followed by Tukey's HSD test for post-hoc comparisons (p < 0.05). RESULTS: For each group, the ESBS and FS, respectively, in MPa were: 1. 17.07 ± 4.52 and 472.69 ± 30.49; 2. 14.98 ± 3.92 and 441.77 ± 61.43; 3. 18.59 ± 5.67 and 186.89 ± 43.89; 4. 16.74 ± 6.27 and 314.41 ± 148.52; 5. 14.38 ± 4.14 and 223.80 ± 77.35; 6. 16.00 ± 5.55 and 287.62 ± 85.91; 7. 16.42 ± 3.67 and 285.35 ± 39.68; 8. 23.24 ± 5.81 and 370.46 ± 29.26; 9. 12.58 ± 4.76 and 87.75 ± 22.87. For most fibers, no significant difference in ESBS was found compared to the control group, except for everStick C&B, which yielded higher ESBS. Nonreinforced composite exhibited the lowest FS, while all fibers positively affected the FS. CONCLUSIONS: Fiber reinforcement of flowable composite does not affect its ESBS. The flexural strength of FRCs is significantly influenced by fiber composition and pattern.

Shear bond strength of orthodontic brackets bonded with a new self-adhering flowable resin composite.

OBJECTIVES: This study aims to assess the shear bond strength (SBS) to enamel and the distribution of failure modes of brackets bonded using a new self-adhering flowable resin composite (Vertise Flow, VF), with or without preliminary phosphoric acid etching (PAE). MATERIALS AND METHODS: Eighty extracted premolars were randomly divided into four groups (n = 20): (1) etch-and-rinse adhesive (E&R), PAE/Transbond XT Primer/Transbond XT Paste (3M Unitek); (2) self-etch adhesive (SE), Transbond Plus Self-Etching Primer (3M Unitek)/Transbond XT Paste; (3) VF; (4) PAE/VF. In each group, 10 bracketed teeth were debonded within 30 min, while the remaining teeth were subjected to thermocycling before testing. SBS and adhesive remnant index were recorded. RESULTS: SE measured significantly lower early SBS than PAE/VF. Early SBSs recorded by VF were slightly higher yet statistically similar to those of E&R. Such levels of adhesion were achieved by VF regardless of preliminary PAE. After thermocycling, VF measured the lowest SBS. When debonded early, VF and SE tended to leave less residues on enamel surface than E&R. After thermocycling, the failure pattern changed significantly for VF and PAE/VF specimens that all exhibited adhesive failures at the tooth-bracket interface. CONCLUSIONS: VF achieved early bracket SBSs similar to E&R. Following thermocycling, VF and PAE/VF manifested a significant decrease in SBS. CLINICAL RELEVANCE: Although the simplified handling and the satisfactory early SBS of VF may prompt its use for bracket bonding, the decrease in retention noted after thermocycling warns that the issue of bond durability should be thoroughly addressed prior to endorsing this clinical application of VF.

Bonding and sealing ability of a new self-adhering flowable composite resin in class I restorations.

OBJECTIVES: The aim of this study is to assess by means of shear bond strength tests (SBS), microleakage analysis (µLKG), and scanning electron microscopy (SEM) the bonding potential and sealing ability of a new self-adhering composite resin. MATERIALS AND METHODS: SBS and µLKG of Vertise Flow (VF, Kerr) were measured and compared to the all-in-one adhesive systems G-Bond (GB, GC), AdheSE One (AO, Ivoclar Vivadent), Adper Easy Bond (EB, 3M ESPE), Xeno V (XV, Dentsply), and iBOND (iB, Heraeus Kulzer). For each system, 20 molars were tested for SBS on dentin (n = 10) and enamel (n = 10). For µLKG assessment, 12 premolars per group were selected and small, box-shaped cavities were made. After restoration, the teeth were immersed in 50 wt% silver nitrate solution for 24 h. For each group, 10 randomly selected specimens were processed for leakage calculations, while two of the specimens were examined under SEM. Between-group differences in SBS to dentin and µLKG were assessed using Kruskal-Wallis analysis of variance followed by the Dunn's Multiple Range test. Enamel SBS data were analyzed with one-way ANOVA, followed by the Tukey test. RESULTS: On dentin and enamel, VF recorded the lowest SBS values that were statistically comparable to those measured by GB, iB, and AO. µLKG analysis showed the lowest percentage of stained interface for VF. Significantly greater extent of infiltration was seen for iB and EB. CONCLUSIONS: Although VF resulted in lower bond strengths values on either dental substrate, better marginal sealing ability was visualized in comparison with all-in-one adhesive systems. CLINICAL RELEVANCE: The results of the present study demonstrated satisfactory in vitro outcome of the self-adhering flowable composite resin VF when used to restore class I cavities.

Influence of selective enamel etching on the bonding effectiveness of a new "all-in-one" adhesive.

PURPOSE: To evaluate in vitro the all-in-one adhesive G-Bond Plus/G-aenial Bond (GBP), used according to the selective enamel etching (SEE) technique, compared to Optibond FL, an etch-and-rinse adhesive tested as control (C). METHODS: 133 molars provided specimens for enamel and dentin shear bond strength (SBS) testing, microleakage measurements in class 5 restorations, and scanning electron microscope observations of demineralization patterns produced by GBP and 37% phosphoric acid (PA). RESULTS: On enamel: C displayed the highest SBS. PA etching significantly increased enamel SBS of GBP. No statistically significant difference in SBS was noted among the bonding procedures on dentin. On both substrates, C revealed the most satisfactory seal. PA pre-etching did not significantly affect the sealing ability of GBP on either substrate.

Post-retentive ability of new flowable resin composites.

PURPOSE: To investigate the applicability of flowable composites as post luting agents by assessing the push-out strength of posts. METHODS: 36 intact single rooted human premolars were selected. The endodontic treatment was performed and half of the specimens were restored with light transmitting posts (DT Light Post Illusion) and the other half with opaque posts (Tech 21 X-OP). In both groups the following combinations of adhesive/cement were tested: OptiBond Solo Plus/Nexus Third Generation (NX3), XP Bond/SureFil SDR Flow (SDR), and Vertise Flow (VF). Push-out test was used to assess the retentive strength of fiber posts, which was expressed in megapascals (MPa). Specimens were analyzed under a stereomicroscope to determine failure mode (adhesive between luting agent and post, adhesive between luting agent and dentin or mixed failure). Push-out data and failure mode distribution were analyzed by two-way ANOVA and Chi-square test, respectively (P< 0.05). RESULTS: The statistical analysis revealed that only the type of luting material significantly influenced push-out bond strength of the post (P< 0.001). SDR (9.00 +/- 2.17 MPa) performed similarly to the control group NX3 (7.15 +/- 1.74 MPa), while VF (4.81 +/- 1.51 MPa) should significantly lower bond strength. Failure modes differed significantly among groups.

Shear-bond strength of a new self-adhering flowable restorative material to dentin of primary molars.

OBJECTIVE: The aim of this study was to evaluate the shear bond strength to dentin of primary molars of a new self-adhering flowable resin composite with two ionomer-based cements and one flowable resin composite in combination with two different adhesive systems. STUDY DESIGN: Fifty primary molars were grinded on the occlusal surface to obtain flat dentin substrate and randomly divided into 5 groups (n = 10): OFL:Phosphoric Acid/Optibond FL/Premise Flow; OAO:Optibond All-In-One/Premise Flowable; II:Polyacrylic Acid/Fuji II; IX:Polyacrylic Acid/Fuji IX; V:Vertise Flow. Cylinders (3mm diameter - 5mm height) of restorative material were built-up in three increments over the dentin surfaces. A shear load was applied until failure. Bond strength values were statistically analysed with Kruskall-Wallis ANOVA followed by Dunn's test (P < .05). Differences in failure mode distribution were assessed with Chi-square (P < .05). RESULTS: OFL and OAO recorded significantly higher bond strengths than the other groups. Adhesive failures were evident in all groups except OFL and OAO, in which also cohesive failures in dentin were observed. CONCLUSIONS: Vertise Flow established on primary dentin bond strengths values similar to those of glass ionomer cements routinely used for restorations of primary teeth. The combination of flowable resin with etch-and-rinse or all-in-one adhesives obtained higher bond strength values, thus involving a more complex handling.

Clinically Relevant Properties of 3D Printable Materials for Intraoral Use in Orthodontics: A Critical Review of the Literature.

The review aimed at analyzing the evidence available on 3D printable materials and techniques used for the fabrication of orthodontic appliances, focusing on materials properties that are clinically relevant. MEDLINE/PubMed, Scopus, and Cochrane Library databases were searched. Starting from an initial retrieval of 669 citations, 47 articles were finally included in the qualitative review. Several articles presented proof-of-concept clinical cases describing the digital workflow to manufacture a variety of appliances. Clinical studies other than these case reports are not available. The fabrication of aligners is the most investigated application of 3D printing in orthodontics, and, among materials, Dental LT Clear Resin (Formlabs) has been tested in several studies, although Tera Harz TC-85 (Graphy) is currently the only material specifically marketed for direct printing of aligners. Tests of the mechanical properties of aligners materials lacked homogeneity in the protocols, while biocompatibility tests failed to assess the influence of intraoral conditions on eluents release. The aesthetic properties of 3D-printed appliances are largely unexplored. The evidence on 3D-printed metallic appliances is also limited. The scientific evidence on 3D printable orthodontic materials and techniques should be strengthened by defining international standards for laboratory testing and by starting the necessary clinical trials.