Impact of recycling on the mechanical properties of nickel-titanium alloy wires and the efficacy of their reuse after cold sterilization.

OBJECTIVE: This study aimed to assess the feasibility of reusing nickel-titanium (NiTi) alloy wires after 6 weeks of intraoral use by evaluating the changes in the load-deflection properties and surface characterization of these alloy wires after cold sterilization by immersion in 2% of acidic glutaraldehyde for 10 h. MATERIAL AND METHODS: Twenty wires each in three groups of G1-as-received wires (ARW), G2-unsterilized used wires, and G3-sterilized used wires (SUW) were tested by the three-point bending test and scanning electron microscopy (SEM). The data were subjected to statistics, one-way analysis of variance, and Bonferroni posthoc test for comparison. RESULTS: Recycling of NiTi wires produced statistically insignificant changes in both the loading and unloading properties of the wires. The forces needed to twist the used wires, that is, G2-(UUW) and G3-(SUW) were lower than G1-(ARW), suggesting lowering of the stiffness of the wires. Superelasticity is well-maintained by G2-(UUW) and G3-(SUW) although there is an insignificant lowering of the forces exerted by them during loading and unloading. SEM demonstrated no increase in the pitting of surfaces in both G2-(UUW) and G3-(SUW); multiple areas were seen to be more smoothened over G2-(UUW) and G3-(SUW) NiTi wires surfaces. CONCLUSION: The findings of this study support the reuse of NiTi wires after 6 weeks of use in oral conditions followed by cold sterilization by immersion in 2% acidic glutaraldehyde for 10 h.

Comparison of stability changes of various palatal implants.

AIM: The aim of this study was to comparatively evaluate stability changes in palatal implants during the early stages of bone healing with chemically modified sandblasted/acid-etched (modSLA) titanium surface compared with a standard sandblasted (SLA) titanium palatal implants. MATERIALS AND METHODS: A statistically significant number (n = 40; 24 females and 16 males) of adult subjects who volunteered and have their informed consent for participating in the study were selected. These volunteers were randomly allocated to the experimental group (modSLA surface) and to the control group (SLA surface) with 20 subjects in each group. Documentation of implant stability was done by assessing resonance frequency analysis (RFA) at implant insertion, followed by subsequent assessments each week till 12th week from baseline (1-12 weeks). RFA values were expressed as an implant stability quotient (ISQ). RESULTS: Immediately after installation of implant, the ISQ values for both surfaces tested were not significantly different and yielded mean values of 75.28 ± 5.23 for the control and 73.16 ± 4.81 for the test surface. In the first 2 weeks after implant installation, both groups presented only small changes and thereafter a reducing trend in the mean ISQ levels. In the test group, after 4 weeks a tendency toward increasing ISQ values was observed, and 6 weeks after surgery the ISQ values corresponded to those after implant insertion. For the SLA control group, the trend changed after fifth week and yielded ISQ values corresponding to the baseline after ninth week. After 12 weeks of observation, the test surface yielded significantly higher stability values of 78.68 ± 2.9 compared with the control implants of 75.5 ± 3.19, respectively. CONCLUSION: The results undoubtedly support and validate the potential for chemical modification of the SLA surface to positively influence the biologic process of osseointegration and also a faster healing.

Evaluation of levels of Interleukin-1b, intensity of pain and tooth movement during canine retraction using different magnitudes of continuous orthodontic force.

AIM: The present study was conducted for the evaluation of Interleukin (IL)-1b levels in human gingival crevicular fluid (GCF), intensity of pain, and the amount of tooth movement measured during canine retraction using different magnitudes of continuous orthodontic force. MATERIALS AND METHOD: A statistically significant number of subjects were included for the study (n = 16, 6 male subjects and 10 female subjects). The age ranged from 18 to 24 years and all were diagnosed with Class I bimaxillary protrusion. They underwent first premolar extractions prior to participating in the study. The maxillary cuspids were then retracted using a continuous force of either 50 or 150 g. This was executed using nickel-titanium coil springs on segmented archwires. The opposite counterpart, that is, mandibular cuspid was used as control. GCF was then drawn from the distal aspect of each tooth at defined time intervals. This was followed by the assessment of IL-1b concentrations, pain intensity, using the visual analogue scale (VAS), and the amount of tooth movement. ANOVA test, Friedman test, and paired t-tests were used for comparisons of IL-1b in GCF, the plaque and gingival indices, and the efficiency of tooth movement on pain perception, respectively. RESULTS: The 150 g group showed the highest level of IL-1b concentration at 24 h from baseline and at 2 with significant differences compared with the control group (P < 0.05). The mean VAS score of pain intensity from the 150 g force was significantly greater than from the 50 g force at 24 h (P < 0.01). CONCLUSION: No significant difference in the amount of tooth movement was found between these two different magnitudes of continuous force at 2 months. A 50 g force could effectively induce tooth movement similar to 150 g with less pain and less inflammation.

Correlation of soft palate morphology to growth pattern: A retrospective cephalometric study.

AIM: The aim of the present study was to evaluate the radiographic length of velum (LV), width of velum (WV), velum angle (AV), depth of pharynx (PD), Need's ratio (NR), inclination angle (AI) in different morphological types of soft palate according to growth patterns in skeletal class I individuals. METHODOLOGY: 80 pretreatment lateral cephalograms of patients with skeletal class I malocclusion (ANB 2--4°) were divided on basis of six types of soft palate and further into three subgroups according to growth pattern and evaluation of LV, WV, angle with the palatal plane, and NR was done. Kruskal--Wallis test was used for the comparison between the groups. RESULTS: Statistically significant difference was verified among all groups for measurement of NR. The highest NR was seen in Crook type of soft palate (mean 0.9). Similarly, the vertical growth pattern in all the six types of soft palate exhibited a higher NR than the average and horizontal growth pattern group; the highest being exhibited by vertical group in type VI (crook shaped). Velopharyngeal insufficiency is directly related to NR. CONCLUSION: Vertical growth pattern has the highest susceptibility to velopharyngeal insuffiency and speech and sleep apnea disorders.

A survey on orthodontic services provided by general dental practitioners.

The aim of this survey-based study was to recognize professional determinants that account for variations in the level of orthodontic services provided and which distinguish providers and nonproviders of orthodontic services. Multiple regression analysis revealed that four practitioner characteristics explained 43% of the variance in the number of orthodontic patients treated. Dentists who treated more orthodontic patients (1) treated more general practice patients, (2) frequently used multiple sources to keep up to date in orthodontics, (3) perceived their patient base to contain more children, and (4) were likely to have attended an orthodontic course. The null hypothesis that selected characteristics of dentists providing orthodontic services were no different from those of dentists not providing orthodontic services was rejected. The provision of orthodontic services was associated with a higher level of continuing orthodontic education and treating more general practice patients, especially children.

Elevated levels of Interleukin (IL)-1ß, IL-6, tumor necrosis factor-α, epidermal growth factor, and ß2-microglobulin levels in gingival crevicular fluid during human Orthodontic tooth movement (OTM).

AIM: The aim of this study was to identify and quantify the various cytokines in human gingival crevicular fluid (GCF), and to investigate the changes in their levels during orthodontic tooth movement (OTM). MATERIALS AND METHODS: A statistically significant no. of subjects (n = 10 and mean age = 15.6 years) were included in the study. A maxillary cuspid of each subject having one treatment for distal orthodontic tooth movement served as the experimental tooth, whereas the contralateral cuspids were used as controls. Gingival crevicular fluid (GCF) around the experimental and the two control teeth was collected from each subject immediately before activation, and at 1, 24, and 168 hours after the initiation of tooth movement. RESULT: ELISAs were used to determine cytokine levels. The concentrations of interleukin (IL)-1lß, IL-6, tumor necrosis factor-α, epidermal growth factor, and ß2-microglobulin were significantly higher in the experimental group than in the controls at 24 hr after the experiment was initiated. All the cytokines remained at baseline levels throughout the experiment for the control groups. CONCLUSION: Since all cytokines in GCF play an important role in the bone remodelling processes in vivo, the present results indicate that the changes in cytokines in GCF are associated with OTM.