Initial Orthodontic Tooth Movement Research Articles

Biomechanical simulation of forces and moments of initial orthodontic tooth movement in dependence on the used archwire system by ROSS (Robot Orthodontic Measurement & Simulation System)

ObjectivesAim of this study was to determine the forces and moments during simulated initial orthodontic tooth movements using a novel biomechanical test setup. MethodsThe test setup consisted of an industrial precision robot with a force-torque sensor, a maxillary model and a control computer and software. Forces and moments acting on the corresponding experimental tooth during the motion simulations were dynamically measured for two 0.016” NiTi round archwires (Sentalloy Light/Sentalloy Medium). Intrusive (#1), rotational (#2) and angular (#3) tooth movements were simulated by a control program based on the principle of force control and executed by the robot. The results were statistically analysed using K–S-test and Mann-Whitney U test with a significance level of α = 5%. ResultsSentalloy Medium archwires generated higher forces and moments than the Sentalloy Light archwires in all simulations. In simulation #1 the mean initial forces/moments reached 1.442 N/6.781 Nmm for the Light archwires and 1.637 N/9.609 Nmm for the Medium archwires. In movement #2 Light archwires generated mean initial forces/moments of 0.302 N/−8.271 Nmm whereas Medium archwires generated 0.432 N/−9.653 Nmm. Simulation #3 showed mean initial forces/moments of −0.122 N/8.477 Nmm from the Light archwires compared to −0.300 N/11.486 Nmm for the Medium archwires. SignificanceThe measured forces and moments were suitable for initial orthodontic tooth movement in simulations #2 and #3, however inadequate in simulation #1. Reduced archwire dimensions (<0.016″) should be selected for initial leveling of vertical malocclusions.

Influence of photobiomodulation on pain perception during initial orthodontic tooth movement

Abstract Introduction Laser in low intensity (LLI) has been used to reduce the discomfort and pain that is triggered by the forces applied during orthodontic treatment. Objective To evaluate the effect of LLI application in the pain perception of periodontal ligament initial compression, during orthodontic tooth movement; and to compare the effect of this therapy between men and women. Material and method The sample consisted of 30 volunteers, who needed orthodontic band placement on mandibular first molars. After insertion of the elastic separators, LLI was applied to the mesial and distal apical region (wavelength 808nm, energy 2J, time 20s and fluency of 8.32J/cm2) and at three points on the root region (wavelength 808nm, energy 1J, time 10s and fluency of 4.16J/cm2) of the first molar (irradiated side) and compared to the contralateral first molar (non-irradiated side), in three time intervals: 0hs, 24hs and 48hs. Pain perception was evaluated by the Visual Analog Scale (VAS), at 0hs, 24hs and 48hs after insertion, with significance of 5%. Result The pain level was observed to be significantly lower (p&lt;0.05) on the irradiated side, irrespective of gender and time. Women presented a significantly higher pain level (p&lt;0.05) than men, irrespective of time and side. There were no significant differences between the time intervals (p&gt;0.05). Conclusion It was concluded that LLI reduced the perception of initial pain in patients in whom compression of the periodontal ligament was promoted by elastic separation, and that women had a greater perception of pain sensitivity in the time intervals studied.

Atorvastatin inhibits osteoclastogenesis and arrests tooth movement.

In addition to their cholesterol-lowering effects, the statin class of drugs appears to enhance osteogenesis and suppress bone resorption, which could be a clinical concern during orthodontic treatment. In this animal study, we aimed to determine whether atorvastatin (ATV) affects orthodontic tooth movement (OTM) through osteoclast inhibition. Furthermore, we analyzed the potential adverse effects of ATV on long-bone turnover and endochondral ossification. Rats were administered ATV (15mg/kg) or saline solution via gavage (n=12 animals/group), starting 2weeks before initial OTM. Tooth displacement was measured after 7, 14, and 21days. Histologic sections of the maxilla and femur were obtained after 14 and 21days of OTM and stained (hematoxylin and eosin; TRAP assay) for histomorphometric analysis. ATV was associated with significant (P<0.05) reductions in OTM and osteoclast counts. Independently of drug administration, OTM increased the number of osteoclasts and reduced the bone-volume ratio compared with the control maxillae without OTM. Long-term statin administration did not appear to affect femoral endochondral ossification. This experimental study showed that the long-term use of ATV can significantly promote osteoclast inhibition and slow the OTM in the first week in rats. Under physiologic conditions, the drug did not affect bone turnover and endochondral ossification.

Differences in IL-1β and IL-6 levels in the gingival crevicular fluid during acute phase of orthodontic tooth movement between juveniles and young adults

Background/Aim. There is little information, about the difference in cytokine levels in the gingival crevicular fluid (GCF) during orthodontic tooth movement (OTM), between juveniles (children) and young adults (adults). The aim of this study was to examine the levels of interleukins IL-1? and IL- 6 in GCF of these two age groups during the acute phase of OTM. Methods. The subjects, 10 children and 10 adults, underwent OTM of a single tooth, with an untreated antagonistic tooth used as the control group. GCF was sampled from both the control and treatment sites right before the beginning (the baseline) and 24 h, 72 h and 168 h upon initiation of OTM. Cytokine levels were determined by enzymelinked immunosorbent assay (ELISA). Results. The levels of both GCF IL-1? and IL-6 showed a bimodal peak during early phase of OTM, at 24 h and 168 h, in both age groups. As the statistic has shown, the increase in IL-1? levels was more prominent after 168 h in treated teeth of children, compared to both children?s control teeth and treated teeth of adults, whilst the GCF IL-6 levels in the same group increased significantly after 24 h, as well as after 168 h, approximately 70 and 55 fold, respectively. In the same time periods the increase of IL-6 levels in GCF of adults was notably lesser, averaging approximately 5 and 10 fold, respectively, compared to the control teeth. In addition, the amount of tooth movement was statistically larger for children than for adults 168 hours upon the initiation of OTM. Conclusion. GCF IL-1? and IL-6 were increasingly expressed during initial phase of OTM in both children and adults. However, excretory response of cytokines in children?s GCF, especially the concentration of IL-6, was at a significantly higher level than that of adults?, which accords to the finding that the initial OTM is faster in children.

Calcitonin gingival crevicular fluid levels and pain discomfort during early orthodontic tooth movement in young patients

ObjectivesTo investigate the previously unreported presence of calcitonin (CT) levels in gingival crevicular fluid (GCF), its variations during initial orthodontic tooth movement in both tension and compression sites, and its possible association with the experienced dental pain. DesignFifteen children (mean age: 12.6 years) requiring orthodontic closure of the upper midline diastema were included. We collected GCF from the compression and tension sites of the upper right central incisor (experimental) and first bicuspid (control), before and after (1h, 24h, 7d, 15d) beginning of treatment. Calcitonin levels were determined by Western blot. Pain intensity was assessed using a visual analogue scale. ResultsCalcitonin levels were higher in the compression site versus the control site at 7d (p=0.014). Intragroup comparisons showed an increment of CT between 1h and 7d (680.81±1672.60pg/30s, p=0.010) in the compression site. No significant changes were found in the tension and control sites. Calcitonin levels and pain intensity were negatively associated during the period from 24h to 15d (r=−0.54, p=0.05). ConclusionsCT levels in the GCF significantly increased in the compression site after the short term after application of orthodontic forces. These changes were negatively associated with the perceived patient's dental pain during the period from 24h to 15d.

Pain intensity and control with fixed orthodontic appliance therapy (A clinical comparative study on Iraqi sample)

The purpose of this prospective, randomized clinical trial was to investigate the level and intensity of patientspain and discomfort, and to compare between the use of Bite Wafer and Paracetamol in reducing pain and discomfort associated with initial orthodontic tooth movement in both adolescents and adults. Sample: 110 subjects with two age groups, 52 adolescents with age range from 12 to less than 18 years and 58 adults with age range 18-24 years, successfully completing the study. For each subject fixed orthodontic appliance (Roth 0.022) was bonded and round 0.014 NiTi arch wire was ligated with elastic ligature. The subjects in the Bite Wafer group were instructed to chew on it whenever they feel pain for the next 7 days, and document the time and effectiveness of it in the questionnaire. The Paracetamol group subjects instructed to use Paracetamol 500mg to relive pain and record times and effectiveness of its use in questionnaire. Results: The peak of pain was occurred in the first day and declined gradually till totally disappeared at the sixth day after initial arch wire placement. A marked reduction of pain intensity was noticed in both adolescents and adults groups, using Bite Wafer, from the first to the sixth day which is much higher than Paracetamol group especially in adolescents. No gender differences (P>0.05) was noticed in this study. Conclusion: Although both Bite Wafer and Paracetamol reduced pain gradually, Bite Wafer reduced pain more obviously and safely in comparison to Paracetamol especially in adolescents.

Evaluation of alkaline phosphatase activity in dental pulp after initial orthodontic tooth movement

Evaluation of alkaline phosphatase activity in dental pulp after initial orthodontic tooth movement

Prospective randomized clinical trial to compare pain levels associated with 2 orthodontic fixed bracket systems

In this randomized clinical trial, we compared pain levels associated with 2 fixed appliance systems during initial orthodontic tooth movement. Sixty-six patients (36 female, 30 male) were randomly allocated to either a conventional twin bracket (Tru Straight, Ormco Europe, Amersfoort, The Netherlands) or a self-ligating bracket (Damon 3, Ormco). Both arches were bonded, and a 0.014-in superelastic copper-nickel-titanium archwire was ligated in position. Pain intensity levels were recorded twice a day, over 7 days, by using 10-cm visual analog scales. Patients also recorded whether analgesia was taken. Contact point displacements were measured on study models to calculate Little's irregularity index. Fifty-two patients (78.8%) completed the trial (84.8% in the Tru Straight group and 72.7% in the Damon 3 group). Patients in the Damon 3 group reported lower mean maximum pain intensity (P = 0.053) and significantly lower mean pain intensity (P = 0.012) than did the Tru Straight patients. Patients who consumed analgesics reported significantly higher mean maximum pain intensity and mean pain intensity than those who did not take analgesia (P <0.001). The Damon 3 patients generally reported lower pain intensity than the Tru Straight patients. Although there were wide interindividual variations, in this study, the Damon 3 appliance resulted in lower pain intensity, on average, when compared with the Tru Straight appliance.

Perception of discomfort during initial orthodontic tooth alignment using a self-ligating or conventional bracket system: a randomized clinical trial

The aim of this study was to compare the degree of discomfort experienced during the period of initial orthodontic tooth movement using Damon3 self-ligating and Synthesis conventional ligating pre-adjusted bracket systems. Sixty-two subjects were recruited from two centres (32 males and 30 females; mean age 16 years, 3 months) with lower incisor irregularity between 5 and 12 mm and a prescribed extraction pattern, including lower first premolar teeth. These subjects were randomly allocated for treatment with either bracket system. Fully ligated Damon3 0.014-inch Cu NiTi archwires were used for initial alignment in both groups. Following archwire insertion, the subjects were given a prepared discomfort diary to complete over the first week, recording discomfort by means of a 100 mm visual analogue scale at 4 hours, 24 hours, 3 days, and 1 week. The subjects also noted any self-prescribed analgesics that were taken during the period of observation. Data were analysed using repeated measures analysis of variance. There were no statistically significant differences in perceived discomfort levels between the two appliances; discomfort did not differ at the first time point and did not develop differently across subsequent measurement times. Overall, this investigation found no evidence to suggest that Damon3 self-ligating brackets are associated with less discomfort than conventional pre-adjusted brackets during initial tooth alignment, regardless of age or gender.

Time-related PDL: viscoelastic response during initial orthodontic tooth movement of a tooth with functioning interproximal contact—A mathematical model

Most anteroposterior orthodontic movements of posterior teeth have to overcome the “resistance” of adjacent teeth with functioning interproximal contacts. The aim of this study was to develop a mathematical model describing initial posterior tooth movement associated with functioning interproximal contacts in relation to the viscoelastic mechanical behavior of the human periodontal ligament (PDL). A linear viscoelastic 2D mathematical model was modified to depict tipping movement around the center of rotation ( C rot) of a premolar where tipping is restrained by adjacent teeth. Equilibrium equations were applied taking into account the sagittal moment developed around the C rot. The constants of the model were analyzed and applied to a numerical model that can simulate short-term tooth creep movement caused by a tipping force. Changes in force magnitude (0.5–3 N) and crown length (6–10 mm) were analyzed until no movement was observed (steady state). Premolar displacement in contact with adjacent teeth showed a non-linear progression over time with an initial sharp tipping movement followed by a transient period of 2.6–7.1 min. As tipping force increased the transient period increased. A similar but smaller effect was observed with an increase in crown length. The premolar initial displacement within the arch (3.2–19.5 μm) is about seven-fold smaller than retraction/protraction movement of an incisor. These suggest reduction in tooth displacement when functioning interproximal contact is present and clinically recommend establishing a space in the direction of tooth displacement before tooth movement.

MMP-13 (collagenase 3) immunolocalisation during initial orthodontic tooth movement in rats

Matrix metalloproteinases (MMPs) are enzymes that play a central role in periodontal ligament (PDL) space remodelling during orthodontic tooth movement. It has previously been shown that messenger RNA levels of MMP-13 increase significantly following the application of orthodontic forces. The aim of the present study was to examine immunolocalisation of MMP-13 and to evaluate if this collagenase is time-dependently and differentially detected within the PDL following the application of orthodontic forces to create areas of compression and tension. This was achieved by placing elastic bands between the maxillary first and second molars of 16 male Sprague-Dawley rats (each weighing 120-200g) for 12 and 24h. The molar-bearing segments were dissected and processed for histological and immunohistochemical examination. Binding of a monoclonal antibody was used to evaluate MMP-13 localization using an indirect streptavidin/biotin immunperoxidase technique. MMP-13 was found to be inducible at the protein level by the application of forces. The PDL and osteoblast-lineage cells showed a time-dependent increase in immunolabelling of MMP-13. Immunolabelling of MMP-13 was detected initially on the compression side, and then on both the compression and the tension sides. Since this increase in MMP-13 immunolabelling occurred very early following the application of an orthodontic force in both PDL and alveolar bone, this would indicate that MMP-13 might play an important role during tooth movement.

Prospective randomized clinical trial comparing the effects of a masticatory bite wafer and avoidance of hard food on pain associated with initial orthodontic tooth movement

The purpose of this prospective, randomized clinical trial was to compare the use of masticatory bite wafers with the avoidance of mastication in reducing pain and discomfort associated with initial orthodontic tooth movement. Eighty-four subjects (mean age, 14.1 years), randomly allocated to a bite-wafer group (BWG) or a reduced-mastication group (RMG), completed the study. In each subject, 1 arch was bonded and ligated with a round austenitic active 0.016-in nickel-titanium wire, and placebo instructions were given. The subjects in the BWG then performed immediate supervised mastication of the wafers for 10 minutes, and they were instructed thereafter to bite on the wafers to prevent pain for the next 7 days. The subjects in the RMG were instructed not to masticate for 3 hours after placement of the fixed appliance and to avoid masticating hard food for 7 days. Each patient's level of anxiety was assessed before treatment with standard psychometric questionnaires. Each patient recorded the level of pain immediately after archwire ligation on a 100-mm visual analogue scale (VAS) and used a pain diary with a verbal rating scale for the next 7 days. No statistically significant differences in the VAS immediately after ligation of the archwires were observed between the 2 groups. The median pain score for the BWG was higher for the first 4 days. The median peak difference was reached on the evening of the first day. At this maximum value, the median pain score of the BWG was higher and statistically significant (P = .006). Although the amount of pain and discomfort reported by the patients undergoing fixed orthodontic therapy varied, more pain was reported by those using bite wafers than by those who avoided masticatory activity after placement of fixed appliances.).