OBJECTIVE: To assess the prevalence of severe external root resorption and its potential
risk factors resulting from orthodontic treatment. METHODS: A randomly selected sample was used. It comprised conventional periapical
radiographs taken in the same radiology center for maxillary and mandibular
incisors before and after active orthodontic treatment of 129 patients, males and
females, treated by means of the Standard Edgewise technique. Two examiners
measured and defined root resorption according to the index proposed by Levander
et al. The degree of external apical root resorption was registered defining
resorption in four degrees of severity. To assess intra and inter-rater
reproducibility, kappa coefficient was used. Chi-square test was used to assess
the relationship between the amount of root resorption and patient's sex, dental
arch (maxillary or mandibular), treatment with or without extractions, treatment
duration, root apex stage (open or closed), root shape, as well as overjet and
overbite at treatment onset. RESULTS: Maxillary central incisors had the highest percentage of severe root resorption,
followed by maxillary lateral incisors and mandibular lateral incisors. Out of 959
teeth, 28 (2.9%) presented severe root resorption. The following risk factors were
observed: anterior maxillary teeth, overjet greater than or equal to 5 mm at
treatment onset, treatment with extractions, prolonged therapy, and degree of apex
formation at treatment onset. CONCLUSION: This study showed that care must be taken in orthodontic treatment involving
extractions, great retraction of maxillary incisors, prolonged therapy, and/or
completely formed apex at orthodontic treatment onset.
Printed models with a regular base or a horseshoe-shaped base with a bar were accurate regardless of the printing technique used. Printed models with a horseshoe-shaped base made with the stereolithography printer had a statistically significant reduction in the transversal dimension that was not found in the models printed with the polyjet technique.
The aim of this study was to evaluate different approaches to deactivating myofascial trigger points (MTPs). Twenty-one women with bilateral MTPs in the masseter muscle were randomly divided into three groups: laser therapy, needle treatment and control. Treatment effectiveness was evaluated after four sessions with intervals ranging between 48 and 72 h. Quantitative and qualitative methods were used to measure pain perception/sensation. The Wilcoxon test based on results expressed on a visual analog scale (VAS) demonstrated a significant (P < 0.05) decrease in pain only in the laser and needle treatments groups, although a significant increase in the pressure pain threshold was evident only for needling with anesthetic injection (P = 0.0469), and laser therapy at a dose of 4 J/cm² (P = 0.0156). Based on these results, it was concluded that four sessions of needling with 2% lidocaine injection with intervals between 48 and 72 h without a vasoconstrictor, or laser therapy at a dose of 4 J/cm², are effective for deactivation of MTPs.
ObjectiveTo compare the influence of archwire material (NiTi, beta-Ti and stainless steel)
and brackets design (self-ligating and conventional) on the frictional force
resistance.Material and MethodsTwo types of brackets (self-ligating brackets - Smartclip, 3M/Unitek - and
conventional brackets - Gemini, 3M/Unitek) with three (0, 5, and 10 degrees) slot
angulation attached with elastomeric ligatures (TP Orthodontics) were tested. All
brackets were tested with archwire 0.019"x0.025" nickel-titanium, beta-titanium,
and stainless steel (Unitek/3M). The mechanical testing was performed with a
universal testing machine eMIC DL 10000 (eMIC Co, Brazil). The wires were pulled
from the bracket slots at a cross-head speed of 3 mm/min until 2 mm
displacement.ResultsSelf-ligating brackets produced significantly lower friction values compared with
those of conventional brackets. Frictional force resistance values were directly
proportional to the increase in the bracket/ wire angulation. With regard to
conventional brackets, stainless steel wires had the lowest friction force values,
followed by nickel-titanium and beta-titanium ones. With regard to self-ligating
brackets, the nickel-titanium wires had the lowest friction values, significantly
lower than those of other materials.Conclusioneven at different angulations, the self-ligating brackets showed significantly
lower friction force values than the conventional brackets. Combined with
nickel-titanium wires, the self-ligating brackets exhibit much lower friction,
possibly due to the contact between nickel-titanium clips and wires of the same
material.
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