Enver Yetkiner

Fatigue resistance, debonding force, and failure type of fiber-reinforced composite, polyethylene ribbon-reinforced, and braided stainless steel wire lingual retainers in vitro.

Objective To analyze the fatigue resistance, debonding force, and failure type of fiber-reinforced composite, polyethylene ribbon-reinforced, and braided stainless steel wire lingual retainers in vitro. Methods Roots of human mandibular central incisors were covered with silicone, mimicking the periodontal ligament, and embedded in polymethylmethacrylate. The specimens (N = 50), with two teeth each, were randomly divided into five groups (n = 10/group) according to the retainer materials: (1) Interlig (E-glass), (2) everStick Ortho (E-glass), (3) DentaPreg Splint (S2-glass), (4) Ribbond (polyethylene), and (5) Quad Cat wire (stainless steel). After the recommended adhesive procedures, the retainers were bonded to the teeth by using flowable composite resin (Tetric Flow). The teeth were subjected to 10,00,000 cyclic loads (8 Hz, 3 - 100 N, 45° angle, under 37 ± 3℃ water) at their incisoproximal contact, and debonding forces were measured with a universal testing machine (1 mm/min crosshead speed). Failure sites were examined under a stereomicroscope (×40 magnification). Data were analyzed by one-way analysis of variance. Results All the specimens survived the cyclic loading. Their mean debonding forces were not significantly different (p > 0.05). The DentaPreg Splint group (80%) showed the highest incidence of complete adhesive debonding, followed by the Interlig group (60%). The everStick Ortho group (80%) presented predominantly partial adhesive debonding. The Quad Cat wire group (50%) presented overlying composite detachment. Conclusions Cyclic loading did not cause debonding. The retainers presented similar debonding forces but different failure types. Braided stainless steel wire retainers presented the most repairable failure type.

Caries infiltrant combined with conventional adhesives for sealing sound enamel in vitro

OBJECTIVE To test the null hypothesis that combining low-viscosity caries infiltrant with conventional adhesive resins would not improve sealing of sound enamel against demineralization in vitro. MATERIALS AND METHODS Bovine enamel discs (N = 60) with diameter of 3 mm were randomly assigned to six groups (n = 10). The discs were etched with 37% phosphoric acid for 30 seconds and treated with resins of different monomer content forming the following groups: (1) Icon (DMG), (2) Transbond XT Primer (3M ESPE), (3) Heliobond (Ivoclar Vivadent), (4) Icon + Transbond XT Primer, and (5) Icon + Heliobond. Untreated etched samples served as the negative control. Specimens were subjected to demineralization by immersion in hydrochloric acid (pH 2.6) for 80 hours. Calcium dissolution into the acid was assessed by colorimetric analysis using Arsenazo III method at 16-hour intervals. Groups presenting high protection against demineralization were subjected to further acidic challenge for 15 days with calcium measurements repeated at 24-hour intervals. Data were analyzed by Kruskal-Wallis test and Mann-Whitney U-test. RESULTS Untreated specimens showed the highest amount of demineralization. Icon and Transbond XT primer decreased the mineral loss significantly compared to the control. Heliobond performed significantly better than both Icon and Transbond XT primer. Combination of Icon both with Transbond XT primer or Heliobond served as the best protective measures and maintained the protective effect for the additional 15-day acidic challenge. CONCLUSIONS Within the limitations of this in vitro study, it could be concluded that the use of low-viscosity caries infiltrant prior to application of the tested conventional adhesives increases their protective effect against demineralization.

Colour improvement and stability of white spot lesions following infiltration, micro-abrasion, or fluoride treatments in vitro.

SUMMARY BACKGROUND/OBJECTIVES White spot lesions (WSLs) are unwelcome side effects of fixed appliances that compromise the treatment outcome. Recently, infiltration of WSLs has been introduced as a viable treatment alternative. The objective was to evaluate the colour improvement of WSLs and their stability against discolouration following infiltration, fluoride, or micro-abrasion treatments in vitro. MATERIALS/METHODS Artificial WSLs were created in bovine enamel (N = 96) using acidic buffer solution (pH 5, 10 days) and were randomly allocated to four groups. Specimens were treated with infiltration (Icon, DMG), fluoride (Elmex Caries Protection, GABA), and micro-abrasion (Opalustre, Ultradent) or remained untreated (control). Groups were discoloured for 24 hours in tea or tea + citric acid. Colour components and visible colour change (L*, a*, b*, ΔE) were measured spectrophotometrically on following time points: baseline, after WSL formation, after treatment, and during discolouration (8, 16, and 24 hours). Data were analysed using Kruskal-Wallis and Mann-Whitney tests. RESULTS WSL formation increased (L*) in all groups. Only infiltration reduced this effect to baseline. Highest ΔE improvement was obtained by infiltration and micro-abrasion followed by fluoride. This improvement was stable only for infiltration during discolouration. L*, a*, and b* changed significantly during discolouration in all groups except infiltration. Within the same treatment group, discolouration solutions did not differ significantly. LIMITATIONS In vitro testing cannot replicate the actual mode of colour improvement or stability but can be used for ranking materials and techniques. CONCLUSIONS/IMPLICATIONS Infiltration and micro-abrasion treatments were capable of diminishing the whitish appearance of WSLs. Only infiltrated WSLs were stable following discolouration challenge.

Stability of two resin combinations used as sealants against toothbrush abrasion and acid challenge in vitro

Abstract Objective. To test the stability of two conventional adhesives when combined with a low-viscosity caries infiltrant used for sealing sound enamel against toothbrush abrasion and acid challenge in vitro. Materials and methods. Bovine enamel discs (Ø = 3 mm) randomly assigned to three groups (n = 10/group) were etched with 37% phosphoric acid for 30 s and treated with resins of different monomer contents forming three test groups: (1) Untreated specimens (Control); (2) Infiltrant (Icon, DMG) + conventional enamel bonding adhesive (Heliobond, Ivoclar Vivadent); and (3) Infiltrant + conventional orthodontic adhesive (Transbond XT Primer, 3M Unitek). All specimens were immersed in hydrochloric acid (pH 2.6) for up to 9 days, during which they were exposed to 1825 toothbrush-strokes per day. Calcium dissolution was assessed using Arsenazo III method at 24-h intervals. Data were analyzed by Kruskal-Wallis and Wilcoxon signed ranks tests. Results. Cumulative calcium dissolution for the untreated specimens (39.75 ± 7.32 μmol/ml) exceeded the sealed groups (Icon + Heliobond: 23.44 ± 7.03 μmol/ml; Icon + Transbond XT Primer: 22.17 ± 5.34 μmol/ml). Untreated specimens presented a relatively constant calcium dissolution rate throughout the experimental period, whereas the sealed groups presented a gradual increase indicating weakening of the seal by toothbrush abrasion. Both sealed groups presented significantly lower daily calcium dissolution at all time points compared to the control, except for Group 2 on the last measurement day. Conclusions. Low-viscosity caries infiltrant application on sound enamel prior to conventional resin application provided a protective effect against enamel demineralization, but this effect was not stable when challenged mechanically by toothbrush abrasion.

Effect of a low-viscosity adhesive resin on the adhesion of metal brackets to enamel etched with hydrochloric or phosphoric acid combined with conventional adhesives.

PURPOSE This study investigated the effect of a low-viscosity adhesive resin (Icon) applied after either hydrochloric (HCl) or phosphoric acid (H3PO4) on the adhesion of metal brackets to enamel. Failure types were analyzed. MATERIALS AND METHODS The crowns of bovine incisors (N = 20) were sectioned mesio-distally and inciso-gingivally, then randomly assigned to 4 groups according to the following protocols to receive mandibular incisor brackets: 1) H3PO4 (37%)+TransbondXT (3M UNITEK); 2) H3PO4 (37%)+Icon+TransbondXT; 3) HCl (15%)+Icon (DMG)+TransbondXT 4) HCl (15%)+Icon+Heliobond (Ivoclar Vivadent)+TransbondXT. Specimens were stored in distilled water at 37°C for 24 h and thermocycled (5000x, 5°C to 55°C). The shear bond strength (SBS) test was performed using a universal testing machine (1 mm/min). Failure types were classified according to the Adhesive Remnant Index (ARI). Contact angles of adhesive resins were measured (n = 5 per adhesive) on ceramic surfaces. RESULTS No significant difference in SBS was observed, implying no difference between combinations of adhesive resins and etching agents (p = 0.712; ANOVA). The Weibull distribution presented significantly lower Weibull modulus (m) of group 3 (m = 2.97) compared to other groups (m = 5.2 to 6.6) (p < 0.05). The mean SBS results (MPa) in descending order were as follows: group 4 (46.7 ± 10.3) > group 1 (45.4 ± 7.9) > group 2 (44.2 ± 10.6) > group 3 (42.6 ± 15.5). While in groups 1, 3, and 4 exclusively an ARI score of 0 (no adhesive left on tooth) was observed, in group 2, only one specimen demonstrated score 1 (less than half of adhesive left on tooth). Contact angle measurements were as follows: Icon (25.86 ± 3.81 degrees), Heliobond (31.98 ± 3.17 degrees), TransbondXT (35 ± 2.21 degrees). CONCLUSION Icon can be safely used with the conventional adhesives tested on surfaces etched with either HCl or H3PO4.

Could readily silanized silica particles substitute silica coating and silanization in conditioning zirconium dioxide for resin adhesion

Abstract This study investigated the effect of particle types with different morphology and surface properties on the wettability and adhesion of resin cement to zirconia. Zirconia specimens (5 × 5 × 1 mm3) were wet polished. Specimens were randomly assigned to one of the following protocols (N = 36, n = 9 per group): Group CON: Control, no surface conditioning; Group AL: Chairside air-abrasion with aluminium trioxide (50 μm Al2O3) + silane; Group SIL: Chairside air-abrasion with alumina particles coated with silica (SIL) (30 μm SiO2, SilJet) + air-drying + silane; Group 4: Chairside air-abrasion with readily silanized silica particles (SILP) (30 μm SiO2, SilJet Plus). Adhesive resin was applied and resin cement (Variolink II, Ivoclar) was bonded using polyethylene moulds and photo-polymerized and aged (thermocycling, 6.000 cycles, 5–55 °C). Shear bond test was performed using Universal Testing Machine (1 mm/min). Pretest failures were considered 0 MPa. Contact angle measurements were performed (n = 2/group, sessile drop with water). Data (MPa) were analyzed (ANOVA, Tukey’s (α = 0.05). Two-parameter Weibull distribution values including the Weibull modulus, scale (m) and shape (0), values were calculated. Contact angle measurements were in descending order as follows: SIL (74°)c < CON (60°)c < AL (51°)b < SILP (40°)a. Bond strength (MPa) with SIL (17.2 ± 4)a and SILP (17.3 ± 1.9)a demonstrated no significant difference (p > 0.05), being higher than AL (8.4 ± 1.5)b and CON (0)c (p < 0.05). Failure types were exclusively adhesive in all groups. Weibull distribution presented the highest shape (0) for SILP (10.8). SILP presented better wettability than AL. SILP provided similar bond strength to SIL. Readily silanized silica particles may substitute for conventional silica coating and silanization.

Effects of different chlorhexidine pretreatments on adhesion of metal brackets in vitro

ObjectiveTo investigate the effect of chlorhexidine applications in various forms and concentrations on adhesion and failure modes of metal brackets in vitro.Material and methodsNinety bovine enamel specimens were allocated to six groups (n=15). Metal brackets were bonded on all specimens after chlorhexidine pre-treatments forming the following groups: (1) untreated specimens (control); (2) 40% varnish (EC40, Biodent BV, Netherlands), remnants removed with brushing mimicking patient cleaning; (3) 40% varnish (EC40), remnants removed with brushing mimicking professional cleaning; (4) 1% varnish (Cervitec Plus, Ivoclar vivadent, Schaan, Liechtenstein), remnants not removed; (5) brushed with% 1 gel (Corsodyl, GlaxoSmithKline, Münchenbuchsee, Germany), remnants not removed; (6) immersed in 0.07% mouthrinse (Corsodyl, GlaxoSmithKline, Münchenbuchsee, Germany), remnant not rinsed. Debonding of brackets was performed using a universal testing machine. Data were analysed using one-way ANOVA and post-hoc Scheffé test.ResultsGroup 4 performed significantly inferior than all the other groups and the control. Group 4 presented the highest number of adhesive failures at the enamel-resin interface whereas in other groups no failures at adhesive-resin interface was observed.ConclusionPresence of chlorhexidine varnish prior to bracket bonding adversely affects adhesion. Concentration of chlorhexidine pre-treatment has no influence on shear bond strength.

Social smile reproducibility using 3-D stereophotogrammetry and reverse engineering technology

OBJECTIVE To assess the range of social smile reproducibility using 3-D stereophotogrammetry and reverse engineering technology. MATERIALS AND METHODS Social smile images of white adolescents (N  =  15, mean age  =  15.4 ±1.5 years; range  =  14-17 years) were obtained using 3dMDFlex (3dMD, Atlanta, Ga). Each participant was asked to produce 16 social smiles at 3-minute intervals. All images were obtained in natural head position. Alignment of images, segmentation of smile area, and 3-D deviation analysis were carried out using Geomagic Control software (3D Systems Inc, Cary, NC). A single image was taken as a reference, and the remaining 15 images were compared with the reference image to evaluate positive and negative deviations. The differences between the mean deviation limits of participants with the highest and the lowest deviations and the total mean deviations were evaluated using Bland-Altman Plots. RESULTS Minimum and maximum deviations of a single image from the reference image were 0.34 and 2.69 mm, respectively. Lowest deviation between two images was within 0.5 mm and 1.54 mm among all participants (mean, 0.96 ± 0.21 mm), and the highest deviation was between 0.41 mm and 2.69 mm (mean, 1.53 ± 0.46 mm). For a single patient, when all alignments were considered together, the mean deviation was between 0.32 ± 0.10 mm and 0.59 ± 0.24 mm. Mean deviation for one image was between 0.14 and 1.21 mm. CONCLUSIONS The range of reproducibility of the social smile presented individual variability, but this variation was not clinically significant or detectable under routine clinical observation.

Influence of Lateral Cephalometric Radiographs on Orthodontic Treatment Planning of Class II Patients

Background: Lateral Cephalometric Radiographs (LCR) are a common decision-making aid in orthodontic treatment planning and are routinely used in clinical practice. The aim of this present study was to test the null hypothesis that LCR evaluation does not alter specific components of orthodontic treatment planning in Class II patients. Materials and Methods: Records of 75 patients, who had been treated at the Department of Orthodontics, Centre of Dental Medicine, University of Zurich comprised the study material. Inclusion criteria were: (1) adolescents between the age of 12-15, (2) permanent dentition with Class II buccal segment relationship (3) absence of craniofacial and dento-alveolar malformations. Fifteen orthodontists from the dental faculties of Istanbul University, Istanbul and Ege University, Izmir filled out Likert-type linear scale questionnaires without knowing that they would repeat the same procedure with and without LCRs at two different time points. Equivalence and clinical relevance were assessed using (%95 CI) Wilcoxon signed rank tests. Results: Extraction decision did not differ between groups (p=0.68). Preference of functional appliance use (p=0.006) and inter-maxillary fixed functional appliance (p=0.043) was different among groups. Conclusion: LCR evaluation has minor influence on treatment planning procedure of Class II patients. It might be beneficial to consider its prescription not in a routine manner but as a supplementary tool considering possible reduction of radiation exposure.

Influence of Lateral Cephalometric Radiography on Treatment Planning and Preferences in Skeletal Open-Bite Patients: Do Lateral Cephalograms Influence Treatment Planning?

Objective To investigate the influence of diagnostic data derived from lateral cephalometric radiographs (LCR) on treatment preferences of specialists planning skeletal open-bite treatment. Methods Diagnostic records of 25 patients who had been treated at the University of Zurich, Department of Orthodontics, between 1988 and 2007 comprised the study material. Inclusion criteria were 1) skeletal open-bite with no marked antero-posterior discrepancy, 2) dental open-bite, and 3) crowding less than 5 mm. Records consisted of extra-intraoral photographs, panoramic-cephalometric X-rays, casts, and results of analyses. Records, with cephalograms of randomly chosen patients removed, were digitally presented to two orthodontists (A and B), and treatment preferences were asked using Likert-type questionnaires. Three months later, the same records were redelivered with missing cephalograms provided and present cephalograms removed with the questionnaire. Data were evaluated for consistency and tendency to extract using Kappa-κ and McNemar tests. Results Orthodontist B had no poor-agreement scores, whereas orthodontist A presented very-poor agreement for headgear use. Both A (κ=0.833) and B (κ=0.737) had good to very-good agreement in terms of extraction decisions. Neither orthodontist had any significant tendency for extraction/non-extraction therapy (A=0.99; B=0.5). Conclusion Information deduced from LCRs had limited influence on treatment planning preferences in skeletal/dental open-bite patients with no marked antero-posterior discrepancy and no influence on extraction/non-extraction decision.