Serena Incerti Parenti

Evaluation of enamel surfaces after bracket debonding: An in-vivo study with scanning electron microscopy

INTRODUCTION The purposes of this in-vivo study were to compare the modes of failure of uncoated and adhesive precoated metal brackets by using the adhesive remnant index, and to assess the quality of the enamel surface after cleanup by using the enamel damage index. METHODS Twelve Victory brackets (group A) and 12 Victory adhesive precoated brackets (group B) (both, 3M Unitek, Monrovia, Calif) were bonded onto the maxillary second premolars of 12 volunteers. The uncoated brackets were bonded with Transbond XT adhesive resin (3M Unitek). Replicas of the teeth were made before bonding (T0), after bracket removal (T1), and after cleanup (T2). Scanning electron microscope images of all labial enamel surfaces were taken at T0, T1, and T2, and these were evaluated according to the adhesive remnant index and the enamel damage index. RESULTS Evaluation of the adhesive remnant index scores with the chi-square test showed no statistically significant difference between the groups. Evaluation of the enamel damage index grades with the sign test for paired samples showed a statistically significant difference (P <0.01) between T0 and T2. CONCLUSIONS Uncoated and precoated brackets exhibited similar debonding patterns. Additionally, the debonding method tested in this study did not restore the original enamel surface, although there was no clinically relevant enamel damage.

Preventive treatment of ectopically erupting maxillary permanent canines by extraction of deciduous canines and first molars: A randomized clinical trial.

INTRODUCTION In this research project, we aimed to compare the effectiveness of single (1 deciduous canine) and double (deciduous canine and first molar) extractions in subjects with retained maxillary permanent canines positioned palatally or centrally in the alveolar crest, at risk for root resorption of adjacent permanent teeth. METHODS Subjects at risk for canine impaction or resorptive situations were randomly assigned to 1 of 2 treatment modalities: single extraction (17 patients, 28 canines) or double extraction (20 patients, 37 canines). Thirty-one patients with 53 canines judged to be not at risk constituted the untreated control group. Panoramic radiographs were taken at the initial observation and after 18 months on average. Between-group statistical comparisons were carried out on the changes in canine inclination and sector location (measured on panoramic radiographs) and on the percentages of successful permanent canine eruptions. RESULTS The double-extraction group showed significant improvements in the success rate and the intrabony position of the permanent canine, in terms of uprighting the canines long axis with a crown movement in a distal direction. CONCLUSIONS Concomitant deciduous canine and first molar extractions proved to be more effective as a preventive approach to promote eruption of retained maxillary permanent canines positioned palatally or centrally.

Prevalence of incidental maxillary sinus findings in Italian orthodontic patients: a retrospective cone-beam computed tomography study

Objectives To determine the prevalence of incidental maxillary sinus findings in a large sample of orthodontic patients by cone-beam computed tomography (CBCT) with a wide field of view and assess the relationships of such abnormalities with age and gender. Methods Five hundred thirteen CBCT scans obtained for orthodontic diagnosis and treatment planning in a Northern Italian population (N = 513; 292 female and 221 male subjects; 1,026 maxillary sinuses) were studied. The frequencies of pseudocysts and mucosal thickening of the maxillary sinus were recorded. Logistic regression analysis was used to determine the influence of age and gender on these abnormalities. Results Pseudocysts were detected in 52 patients (10.1%) and 59 sinuses (5.75%). Mucosal thickening was observed in 206 patients (40.1%) and 258 sinuses (25.1%). Gender and age were significantly associated with pseudocysts (p = 0.027) and mucosal thickening (p < 0.001), respectively. Conclusions Half of the orthodontic patients had incidental maxillary sinus findings. Men were more likely to show pseudocysts, and older patients (aged 41 - 60 years) were more likely to show mucosal thickening.

Effects of thread shape on the pullout strength of miniscrews.

INTRODUCTION The aim of this study was to determine the effects of variations in thread shape on the axial pullout strength of orthodontic miniscrews. METHODS A total of 35 miniscrews, 7 of each design being considered, were tested by performing pullout tests on a synthetic bone support. We used self-tapping and self-drilling miniscrews having a diameter of 2 mm and a thread shaft length of 12 mm (the longest and the largest supplied by the manufacturer). A buttress reverse thread shape served as the control design and was tested against 4 experimental designs, each manufactured with a modification in thread shape while maintaining all other characteristics. The experimental groups had the following thread designs: buttress, 75° joint profile, rounded, and trapezoidal. RESULTS The control group with a buttress reverse thread shape had consistently higher pullout strength values than did the other designs. A statistically significant reduction in pullout force was found between the buttress reverse and the buttress thread miniscrews. CONCLUSIONS Thread design influenced the resistance to pullout of the orthodontic miniscrews. The buttress reverse thread shape provided the greatest pullout strength.

Percentiles relative to maxillary permanent canine inclination by age: A radiologic study

INTRODUCTION Few studies have investigated developmental norms for maxillary permanent canine eruption. In this observational cross-sectional study, we aimed to provide an age-related description of the percentiles relative to canine inclination in a large sample of nonorthodontic patients. Associations between inclination and sector were also analyzed. METHODS Canine inclination and sector location were measured on 1020 panoramic radiographs obtained from subjects of white ancestry aged between 8 and 11 years not seeking orthodontic treatment. The total sample comprised 2037 canines. RESULTS Canine inclination increases between 8 and 9 years and decreases between 9 and 11 years. The greatest value for each percentile is at 9 years. A linear model should be hypothesized for differences in canine inclination between 2 successive ages in correspondence to each percentile. The proportion of sector 2 canines decreases and that of sector 1 increases with age. In the same age group, the inclination generally decreases as the sector decreases. CONCLUSIONS Percentiles by age show the average canine inclination in a certain population. Further studies are required to verify whether percentiles can be a diagnostic aid for determining normal canine inclination at a given age and for quantifying the risk of canine impaction or adjacent root resorption.

Combined effects of repeated oral hygiene motivation and type of toothbrush on orthodontic patients: A blind randomized clinical trial

OBJECTIVE To investigate the effects on plaque index (PI) scores of manual or electric toothbrush with or without repeated oral hygiene instructions (OHI) and motivation on patients wearing fixed orthodontic appliances. MATERIALS AND METHODS One month after the orthodontic fixed appliance bonding on both arches, 60 patients were randomly assigned to four groups; groups E1 (n  =  15) and E2 (n  =  15) received a powered rotating-oscillating toothbrush, and groups M1 (n  =  15) and M2 (n  =  15) received a manual toothbrush. Groups E1 and M1 received OHI and motivation at baseline (T0) and after 4, 8, 12, 16, and 20 weeks (T4, T8, T12, T16, and T20, respectively) by a Registered Dental Hygienist; groups E2 and M2 received OHI and motivation only at baseline. At each time point a blinded examiner scored plaque of all teeth using the modified Quigley-Hein PI. RESULTS In all groups the PI score decreased significantly over time, and there were differences among groups at T8, T12, T16, and T20. At T8, PI scores of group E1 were lower than those of group E2, and at T12, T16, and T20, PI scores of groups M1 and E1 were lower compared to those of groups M2 and E2. A linear mixed model showed that the effect of repeated OHI and motivation during time was statistically significant, independently from the use of manual or electric toothbrush. CONCLUSIONS The present results showed that repeated OHI and motivation are crucial in reducing PI score in orthodontic patients, independent of the type of toothbrush used.

Different doses of low-level laser irradiation modulate the in vitro response of osteoblast-like cells

Abstract. Because osteoblasts play a key role in bone remodeling and the influence of low-level laser therapy on this process is not clear, Saos-2 human osteoblast-like cells were irradiated by a gallium–aluminum–arsenide diode laser (915 nm) for 10, 48, 96, 193, and 482 s using doses 1, 5, 10, 20, and 50  J/cm2, respectively. A control group was not irradiated. Morphology, viability, and cytotoxicity analyses were carried out after 1 hr, 1 day, and 3 days. Deoxyribose nucleic acid (DNA) content and release of vascular endothelial growth factor (VEGF), receptor activator of nuclear factor kappa B ligand (RANKL), and osteoprotegerin (OPG) were evaluated. Viability was modulated by laser irradiation in a dose-dependent manner, with 10  J/cm2 inducing a biostimulatory response and 20 to 50  J/cm2 determining a bioinhibitory and cytotoxic effect. Accordingly, DNA content was generally increased for the 10  J/cm2 dose and decreased for the 50  J/cm2 dose. A rapid and transitory trend toward increased RANKL/OPG ratio and a tendency toward a delayed increase in VEGF release for doses of 1 to 10  J/cm2 was found. Further investigations using the biostimulatory dose of 10  J/cm2 emerged from this study are needed to establish the ideal treatment regimens in the laboratory as well as in clinical practice.

Effect of low-level laser irradiation on osteoblast-like cells cultured on porous hydroxyapatite scaffolds

OBJECTIVE To determine the effect of laser irradiation at a low dose on human osteoblastlike cells. MATERIALS AND METHODS 32 porous hydroxyapatite scaffolds currently used for bone tissue engineering were seeded with MG63 cells and irradiated or not with a GaAlAs diode laser (wavelength 915 nm, dose 2 J/cm2) using different power density and exposure duration. RESULTS After 72-h incubation, cells showed well spread morphology and good adhesion on both laser-treated and untreated scaffolds. Laser irradiation did not interfere in cell viability and proliferation as compared with the non-irradiated controls. CONCLUSION This study suggests that there is no effect of 915 nm laser irradiation at a dose of 2 J/cm2 on the proliferation rate of MG63 cells. Future investigations are needed to compare different dose and wavelength regimens in order to determine the optimal set of laser parameters for maximum cell yield and safe clinical application.

Onychophagia and postorthodontic isolated gingival recession: diagnosis and treatment.

This clinical report describes the diagnosis and the management of isolated-type recession defects of complex etiology in 2 healthy postorthodontic patients. The lesions were confined to 1 mandibular incisor and were associated with an abnormal buccolingual inclination of the affected tooth despite a lingual retainer made with a round stainless steel twisted wire. After careful questioning, it was determined that the recession defects were indirect effects of habitual onychophagia. The concomitant fingernail-biting habit and the lingual bonded retainer led to the indirect development of bone dehiscence and, consequently, gingival recession.

Effect of soft drinks on the physical and chemical features of nickel-titanium-based orthodontic wires

Abstract Objective. The purpose of this study was to evaluate the effect of three popular soft drinks on the Youngs modulus, hardness, surface topography and chemical composition of widely used nickel-titanium-based orthodontic wires. Materials and methods. Thirty-two specimens (20 mm in length) were cut from the straight portion of pre-formed 0.019 × 0.025 inch Nitinol Heat-Activated archwires and randomly divided into four groups of eight specimens each: Group A1 (Coca Cola® regular); Group A2 (Santal® orange juice); Group A3 (Gatorade®); Group B (distilled, deionized water; dH2O). Each specimen was immersed in 10 ml of one of the soft drinks or dH2O, control, for 60 min, at 37°C. At the end of the soaking time, the Youngs modulus and hardness were determined using a nanoindenter. Scanning Electron Microscope–Energy Dispersive Spectroscopy (SEM-EDS) was used to characterize the effects on the topography and chemical composition of the wires. Results. No statistically significant differences were found between the groups either in the Youngs modulus or in hardness after the selected soaking protocol. Besides some surface colour changes, the topography and the chemical composition of the wires were not affected by the immersion in any of the chosen soft drinks. Conclusions. These in-vitro results suggest that the consumption of soft drinks cannot be acknowledged as one possible reason for the degradation of the physical and chemical properties of heat activated nickel titanium orthodontic wires in patients undergoing fixed orthodontic treatment.