Nursel Arici

Effects of thermocycling on the bond strength of a resin-modified glass ionomer cement: an in vitro comparative study.

This study investigated the effects of thermally induced stresses (thermocycling) on the shear bond strength of resin-modified, chemically cured, glass ionomer cement for use as an orthodontic bonding agent. A conventional no-mix composite resin was also used as a control. Mesh-based metal orthodontic brackets were bonded to extracted human premolars using either the resin-modified glass ionomer cement or the no-mix composite resin. Specimens were stored either in water at 37 degrees C for 24 hours for baseline data or thermocycled between 5 degrees C and 55 degrees C for 200 and 20,000 cycles before testing the in vitro shear bond strengths. Thermocycling reduced shear bond strengths for all specimens. The resin-modified glass ionomer cement showed a 11.1% decrease after 200 thermocycles and 26.5% decrease after 20,000 thermocycles, whereas the no-mix adhesive resin showed only 5.7% and 17.9% reductions, respectively. Analysis of variance showed statistically significant differences between the mean shear bond strengths of the groups at the P < .001 level of significance. For the resin-modified glass ionomer cement groups, the predominant bond failure site was at the bracket-adhesive interface. The results of this study suggest strongly that resin-modified glass ionomer cements offer a viable alternative to conventional no-mix composite resins, with satisfactory in vitro shear bond strength even after 20,000 thermocycles.

Effects of fixed functional appliance treatment on the temporomandibular joint

INTRODUCTION In this study, we tested the hypothesis that fixed functional appliance treatment in a group of Class II Division 1 patients with mandibular retrusion changes the condyle position in the glenoid fossa. METHODS Transverse computed tomography images were taken of the temporomandibular joint region in 60 children with Class II Division 1 malocclusion. Thirty randomly selected patients were treated with a fixed functional orthodontic appliance (Forsus nitinol flat-spring, 3M Unitek Corp, Monrovia, Calif) for 7 months; another 30 patients without treatment were used as controls. Computed tomography images taken at the beginning and end of fixed functional appliance treatment were used for estimating the condyle-glenoid fossa relationship, including the volumes of condyle, glenoid fossa, and anterior and posterior joint spaces. RESULTS Although the volumes of the condyle and glenoid fossa increased more in the study group than in the control group, the differences were not statistically significant. However, statistically significant differences were found between the groups in the volumes of the anterior and posterior joint spaces (P < 0.05). CONCLUSIONS When the volumes of the anterior and posterior joint spaces changed, the condyle was more posteriorly positioned in the glenoid fossa in the study group than in the control group.

The clinical and laboratory effects of bracket type during canine distalization with sliding mechanics

OBJECTIVE To compare the extent of canine movement with sliding mechanics between a self-ligating (SC) bracket and a modified twin design (MT) bracket. To test the in vitro coefficient of friction (COFs) of these two metal brackets on 0.019- × 0.025-inch, stainless-steel arch wires. MATERIALS AND METHODS For the clinical portion of this study, a split-mouth design was used to bond the brackets of 19 patients. Canine distalization was achieved on a 0.019- × 0.025-inch, stainless-steel arch wire with a nickel-titanium, closed-coil spring strained between a mini-screw and a canine bracket. The linear and angular measurements were performed using lateral cephalometric radiographs taken before and after canine distalization. A tribometer was also used to measure the COFs of the bracket types in vitro. For comparisons, Students t-tests for paired and unpaired samples were used at the 95% confidence level. RESULTS The extent of canine movement and the changes in the canine and molar teeth angles were not significantly different between the SC and MT brackets. After 8 weeks, the mean canine movements were 1.83 and 1.89 mm in the maxilla and 1.79 mm and 1.70 mm in the mandible with the SC and MT brackets, respectively. The mean COF of the MT brackets (0.21) was significantly lower than that of the SC brackets (0.37) during in vitro testing. CONCLUSION It is suggested that the rate of canine distalization was not different between the two groups, although in vitro COFs of the SC bracket was higher.

Adhesive thickness effects on the bond strength of a light-cured resin-modified glass ionomer cement.

These in vitro studies investigated the effect of adhesive thickness on the tensile and shear bond strength of a light-cured, resin-modified glass-ionomer cement (FO). A light-cured conventional composite resin (CO) was used as the control material. Mesh-based metal brackets were bonded to extracted human premolars using FO and CO. The adhesive thickness was controlled by a special device and 0, 0.25, and 0.5 mm thicknesses were tested for both bonding agents. All bonded specimens were stored in distilled water at 37 degrees C for 48 hours and thermocycled between 5 degrees C and 55 degrees C for 200 cycles before testing. Analysis of variance showed that bond strength was significantly affected by the adhesive thickness (P < .001) and type of adhesive (P = .001). There were statistically significant differences between the mean bond strengths of the groups at the P < .05 level of significance. For all adhesive thicknesses, CO had higher bond strength values than those of FO in both test modes. The bond strength values were also analyzed using a Weibull analysis, which showed the most favorable adhesive thickness, and the 5% and 90% probabilities of failures was 0.25 mm in the FO groups. Bracket-adhesive interface failure was predominant for all groups in tensile testing, but enamel-adhesive interface failures increased with increased adhesive thickness in shear testing for the FO. This study suggests that adhesive thickness under a bracket could be particularly important when using a FO in direct bonding.

An evaluation of factors associated with persistent primary teeth

The aim of the present study was to investigate the reasons for the persistence of primary teeth and also use panoramic radiography to determine the characteristics of persistence teeth. Four-hundred and twenty-six panoramic radiographies, which diagnosed one or more retained primary teeth, were selected from 100,577 panoramic radiographic image files from nine clinics and six different cities in Turkey. The selected radiographies were evaluated to determine the reasons for the persistence of primary teeth; furthermore, this study analyzed the characteristics of the retained primary teeth including tooth type, number, location, and root resorption, and whether, or not, the primary teeth showed evidence of pathological conditions, such as periodontal problems, caries, ankylosis, infra-occlusions, or tipping of the adjacent permanent teeth. Six hundred and seventy-seven retained primary teeth were determined in 426 patients (148 males and 278 females). Retained primary teeth were found most frequently in the mandible rather than the maxilla and the left side was more frequently affected than the right side. Level 1 was found as a most frequently encountered root resorption level. Within the limitation of the present study, the most common type of persistent primary teeth seen on the dental arch were mandibular primary second molars, followed by maxillary primary canines. The most frequent reason for the persistence was the congenital absence of successors to the primary teeth, followed by impaction of the successor teeth.

Comparison of the frictional characteristics of aesthetic orthodontic brackets measured using a modified in vitro technique.

Objective The coefficients of friction (COFs) of aesthetic ceramic and stainless steel brackets used in conjunction with stainless steel archwires were investigated using a modified linear tribometer and special computer software, and the effects of the bracket slot size (0.018 inches [in] or 0.022 in) and materials (ceramic or metal) on the COF were determined. Methods Four types of ceramic (one with a stainless steel slot) and one conventional stainless steel bracket were tested with two types of archwire sizes: a 0.017 × 0.025-in wire in the 0.018-in slots and a 0.019 × 0.025-in wire in the 0.022-in slot brackets. For pairwise comparisons between the 0.018-in and 0.022-in slot sizes in the same bracket, an independent sample t-test was used. One-way and two-way analysis of variance (ANOVA) and Tukeys post-hoc test at the 95% confidence level (α = 0.05) were also used for statistical analyses. Results There were significant differences between the 0.022-in and 0.018-in slot sizes for the same brand of bracket. ANOVA also showed that both slot size and bracket slot material had significant effects on COF values (p < 0.001). The ceramic bracket with a 0.022-in stainless steel slot showed the lowest mean COF (µ = 0.18), followed by the conventional stainless steel bracket with a 0.022-in slot (µ = 0.21). The monocrystalline alumina ceramic bracket with a 0.018-in slot had the highest COF (µ = 0.85). Conclusions Brackets with stainless steel slots exhibit lower COFs than ceramic slot brackets. All brackets show lower COFs as the slot size increases.

Assessment of the Confidence of the Adhesive Remnant Index Score With Different Methods

ABSTRACT Objective: The purpose of this in vitro study was to investigate the reliability of the adhesive remnant index (ARI) score system with different assessment methods and to test the compatibility of the estimators. Materials and Methods: Sixty-eight human premolars were used in this study. The premolar brackets (SmartClip, 3M Unitek, Monrovia, CA, USA) were bonded with a light cure adhesive (Transbond XT, 3M Unitek). Brackets were debonded using a Lloyd LRX testing machine (Lloyd Instruments Plc., Fareham, Hampshire, UK). Special image analysis software with ×20 magnification and naked-eye assessment methods were used to evaluate the adhesive remnant. Four different investigators scored the same samples according to a 4-point scale. The Kendall rank correlation coefficient was used to test the reliability of the estimators scores. The Friedman test, followed by the Wilcoxon signed-ranks test, was used to investigate significant differences in the ARI scores between the different assessment methods...

Using Hemostatic Agents During Orthodontic Bonding: An In Vitro Study

ABSTRACT Objective: The aim of this in vitro study was to compare the effect of a traditional hemostatic agent on the shear bond strength (SBS) of conventional and self-etching bonding systems to find an efficient procedure for orthodontic bonding. Material and Methods: Extracted human premolars (n=108) were divided into 6 equal groups. Conventional light cure primer was used in groups 1, 2, and 3. Acid etching and primer were applied directly in group 1. Enamel surfaces were covered with a Ankaferd Blood Stopper (ABS), which was used as a hemostatic agent in groups 2 and 3. Orthophosphoric acid was applied on ABS-covered enamel in group 2. Before the acid was applied, the enamel surface was cleaned with wet surgical gauze in group 3. A self-etching primer was used in groups 4, 5, and 6. Similar to the first 3 groups, primer was applied on the enamel surface in group 4. Samples were covered with ABS before the primer was applied in groups 4 and 5. The ABS residue was cleaned with gauze before primer appli...

The Radiological and Stereological Analysis of the Effect of Low-Level Laser Therapy on the Mandibular Midline Distraction Osteogenesis.

Objective:The aim of this study was to evaluate the effect of low level laser therapy (LLLT) on bone mineral density by using high-resolution computerized tomography (HR-CT) and stereology in patients subjected to mandibular midline distraction. Methods:Nine patients between the ages of 13 and 16 years with mandibular transverse deficiency (>5 mm) were evaluated. Mandibular midline distraction osteogenesis was performed for all the patients. The patients were divided into 2 groups: the control group (n = 4) and the laser group (n = 5). GaAlAs, 830 nm wavelength, power of 40 mW, energy of 8.4 J/cm2 dose per spot, was directly applied from 2 points on the mandibular midline. The laser was applied in 8 treatment sessions at 48-hour intervals. Bone mineral density and volume of the newly formed bone were analyzed using HR-CT and stereological methods. Results:A higher bone mineral density rate was found in the laser group (P < 0.05). A higher newly formed immature bone rate was found in the control group (P < 0.001). These findings suggest that more mature bone may also have a greater mineral organization than that of immature newly formed bone, which is shown by HR-CT and stereological results. Conclusions:The retention period can be shortened and mineralization may be increased by using LLLT in mandibular distraction osteogenesis.

Interdisciplinary approach to treating a patient with amelogenesis imperfecta: A clinical report

Amelogenesis imperfecta is a rare hereditary condition in which enamel structure without evidence of systemic disorders. Amelogenesis imperfecta is a disorder, requiring treatment due to esthetic, functional and related psychosocial problems. This article represents, a patient that referred to our clinic suffering from amelogenesis imperfect who successfully overcame the esthetic, functional and psychosocial problems by receiving multidisciplinary team rehabilitation.