Extraction Space Closure Research Articles

A finite element analysis of the effects of archwire size on orthodontic tooth movement in extraction space closure with miniscrew sliding mechanics

BackgroundSliding mechanics with miniscrews is recently used for extraction space closure. The purpose of this study was to elucidate how and why the archwire size affects long-term tooth movement in miniscrew sliding mechanics.MethodsLong-term orthodontic tooth movements were simulated based on a remodeling law of the alveolar bone by using a finite element method, in which the bracket rotated freely within a clearance gap (a play) of the archwire-bracket slot. The archwire size was changed to 0.021, 0.018, and 0.016 in. for the 0.022-in. bracket.ResultLingual crown tipping and extrusion of the incisors increased with decreasing the archwire size. Movements of the posterior teeth were approximately the same irrespective of archwire size.ConclusionsWhen decreasing the archwire size, a play of the archwire-bracket slot, as well as the elastic deformation of the archwire, resulted in lingual tipping of the incisors. This tipping led to extrusion of the incisors.

Effect of archwire stiffness and friction on maxillary posterior segment displacement during anterior segment retraction: A three-dimensional finite element analysis.

ObjectiveSliding mechanics using orthodontic miniscrews is widely used to stabilize the anchorage during extraction space closure. However, previous studies have reported that both posterior segment displacement and anterior segment displacement are possible, depending on the mechanical properties of the archwire. The present study aimed to investigate the effect of archwire stiffness and friction change on the displacement pattern of the maxillary posterior segment during anterior segment retraction with orthodontic miniscrews in sliding mechanics.MethodsA three-dimensional finite element model was constructed. The retraction point was set at the archwire level between the lateral incisor and canine, and the orthodontic miniscrew was located at a height of 8 mm from the archwire between the second premolar and first molar. Archwire stiffness was simulated with rectangular stainless steel wires and a rigid body was used as a control. Various friction levels were set for the surface contact model. Displacement patterns for the posterior and anterior segments were compared between the conditions.ResultsBoth the anterior and posterior segments exhibited backward rotation, regardless of archwire stiffness or friction. Among the conditions tested in this study, the least undesirable rotation was found with low archwire stiffness and low friction.ConclusionsPosterior segment displacement may be unavoidable but reducing the stiffness and friction of the main archwire may minimize unwanted rotations during extraction space closure.

Orthodontic extraction space closure with and without socket preservation: a comparative case analysis.

Preorthodontic socket preservation after tooth extraction is intended to enhance favorable dentoalveolar ridge morphology and architecture, and facilitate orthodontic tooth movement (OTM) and extraction space closure. This 13-year-old skeletal Class II case presents a unique opportunity to evaluate and compare the OTM extraction space closure by means of a split-mouth analysis in a single patient. The comprehensive orthodontic-periodontal treatment included nonsimultaneous extraction of the bilateral periodontally compromised mandibular first molars and the eruption of bilateral impacted mandibular canines. While the right post-extraction space underwent a natural healing process, the left one was grafted using 4BONE BCH (hydroxyapatite β-tricalcium phosphate [HA-β-TCP], HA 60%, and β-TCP 40%). The 3-year multidisciplinary treatment approach resulted in Class I relationships on the right side and Class II on the left side, improved facial appearance, and dento-skeletal jaw relationships. However, a 3-mm residual alveolar space remained unclosed on the grafted left-site, along with an unerupted left third molar. This split-mouth comparative analysis of the orthodontic space closure demonstrated a significant clinical difference in the outcome. Preorthodontic placement of HA-β-TCP grafting material on the left segment, proved to be an obstacle for OTM extraction space closure, hindering the establishment of good occlusion.

Comparison of frictional forces during the closure of extraction spaces in passive self-ligating brackets and conventionally ligated brackets using the finite element method.

BackgroundThis study compared the frictional force resulting from the bracket/archwire interface and the stress at the root/periodontal ligament/bone interface, between passive self-ligating brackets and conventionally ligated brackets, during the space closure stage.Material and MethodsA cone beam tomography was taken to a female patient that required extraction of upper first premolars and passive self-ligating system; three months after its activation, a cone beam tomography was taken again. The designs of the maxillary bone and the entire system were possible through tomography images and stereomicroscopic photographs. Validation of the Finite Element Method (FEM) was achieved comparing the amount of movement seen through tomography images and the FEM. Space closure was simulated for each system through the FEM and a comparison was made between the frictional force at the bracket/archwire interface, and the root/periodontal ligament/bone interface.ResultsThe most significant representation of frictional force at bracket/archwire interface and bone stress was found at the conventionally ligated system, while the passive self-ligating system accounted for the highest distribution of stress over the root.ConclusionsThe FEM is an accurate tool used to quantify frictional force and stress concentration during the orthodontic closure. The passive self-ligating system was seen less frictional during the closure state compared to conventional brackets. Key words:Friction, orthodontic bracket, finite element analysis.

Effectiveness of anchorage with temporary anchorage devices during anterior maxillary tooth retraction: A randomized clinical trial.

ObjectiveThis study evaluated the efficiency of anchorage provided by temporary anchorage devices (TADs) in maxillary bicuspid extraction cases during retraction of the anterior teeth using a fixed appliance.MethodsPatients aged 12 to 50 years with malocclusion for which bilateral first or second maxillary bicuspid extractions were indicated were included in the study and randomly allocated to the TAD or control groups. Retraction of the anterior teeth was achieved using skeletal anchorage in the TAD group and conventional dental anchorage in the control group. A computed tomography (CT) scan was performed after alignment of teeth, and a second CT scan was performed at the end of extraction space closure in both groups. A three-dimensional superimposition was performed to visualize and quantify the maxillary first molar movement during the retraction phase, which was the primary outcome, and the stability of TAD movement, which served as the secondary outcome.ResultsThirty-four patients (17 in each group) underwent the final analysis. The two groups showed a significant difference in the movement of the first maxillary molars, with less significant anchorage loss in the TAD group than that in the control group. In addition, TAD movement showed only a slight mesial movement on the labial side. On the palatal side, the mesial TAD movement was greater.ConclusionsIn comparison with conventional dental anchorage, TADs can be considered an efficient source of anchorage during retraction of maxillary anterior teeth. TADs remain stable when correctly placed in the bone during the anterior tooth retraction phase.

Comparative study of the rate of tooth movement between corticotomy and piezocision to facilitate en masse retraction in bimaxillary protrusion

Objective: The aim of this study was to evaluate the rate of orthodontic tooth movement and the time needed for extraction space closure when corticotomy and piezocision were used to facilitate en-masse retraction in bimaxillary protrusion cases. Subjects and Methods: The sample of this study consisted of twenty subjects having Class I malocclusion with bimaxillary protrusion and requiring extraction of four first premolars and en-masse retraction of the anterior segments on both arches. The sample was randomly divided into two equal groups; group I:corticotomy was performed by using piezosurgery through flap reflection and group II: corticotomy was performed by using piezocision (flapless corticotomy). Study models were obtained just before surgery and in every month for 6 months after surgery to measure the rate of orthodontic tooth movement in both groups. After completing the en-masse retraction, the retraction time in months was recorded for the right and left sides and averaged. Results: Group I showed a statistically significant shorter retraction time than group II. Group I showed a statistically significant increase in the rate of tooth movement from the 2nd to the 5th month in the upper arch. For the lower arch, group I exhibited a significant increase in the rate of tooth movement in the 4th month. Conclusion: Corticotomy involving flap reflection showed a shorter retraction time and higher rates of tooth movement than piezocision during en-masse retraction.

Velocity of orthodontic active space closure with and without photobiomodulation therapy: a single-center, cluster randomized clinical trial

The objective of this two-arm, parallel randomized clinical trial was to assess the effectiveness of low-level light therapy (photobiomodulation) using an intraoral light-emitting diode (LED) device with respect to accelerating premolar extraction space closure during en masse retraction. This trial was conducted between January 2013 and February 2014 at the European Univeristy College Department of Orthodontics. The study included 60 orthodontic patients (age range, 11.3–47.1 years; mean age, 20.4 years) with premolar extractions. Patients (n = 60) were randomized into the photobiomodulation (PBM) group (n = 30) or the control group (n = 30). Eligibility criteria included no active caries, good oral hygiene, and an extraction orthodontic treatment plan. Extraction spaces were closed using NiTi closed springs utilizing 150 g of force. Extraction spaces were measured on study models at the beginning of en masse retraction (T1) and at space closure completion (T2). All measurements were obtained by a single investigator who was blinded to the group allocation of study models. The primary outcome was the velocity of extraction space closure (mm/month) during the period of en masse retraction. Treatment allocation was implemented using randomization with 2 major blocks of 30 patients, by asking each patient to draw a sealed envelope (n = 60) indicating allocation to the PBM or control group. The allocation ratio was 1:1. The PBM group of patients (n = 30) was treated with intraoral infrared LED light therapy for 3 min per arch per day using OrthoPulse™ (Biolux Research®, Vancouver, Canada) producing a continuous 850-nm wavelength and a power density of 33 mW/cm2 per arch per day to achieve a total energy density of approximately 6 J/cm2 at the surface of the device during the en masse retraction phase; patients were required to maintain over 80% compliance with daily device use. Compliance was monitored by the device controller’s onboard computer. Sixty patients were randomized between the two groups. Fifteen patients dropped out during the study period, but were accounted for in the primary analysis as an intention to treat (ITT) analysis through multiple imputations. Mean age for the PBM and control groups were 20.7 and 22 years, respectively. Patients treated with PBM exhibited a statistically significant higher velocity of space closure by 0.22 mm/month (95% confidence interval [CI], 0.09–0.49; p < 0.01). The mean velocity of space closure in the PBM group was 1.08 mm/month (SD 0.54) compared with the control group’s 0.86 mm/month (SD 0.42). A secondary analysis was conducted on the 45 patients that reached the primary outcome and did not deviate from the study protocol (15 dropout patients removed), providing 123 extraction spaces for the analysis—23 patients from the PBM group and 22 patients from the control group. No serious harms due to treatments were encountered during the study period. The results of this study suggest that PBM therapy accelerated the rate of orthodontic space closure during en masse retraction. This trial and its protocol were not registered on a publicly accessible registry.

A Comparison of the Rate of Retraction with Low-level Laser Therapy and Conventional Retraction Technique.

Background and Objectives:A major concern of orthodontic patients is treatment time. Reducing the treatment time requires increasing the rate of orthodontic tooth movement. Research has proved that bone resorption is the rate-limiting step in tooth movement. Therefore, any procedure that potentiates osteoclastic activity is capable of increasing the rate of orthodontic tooth movement. Low-level laser has been indicated to have the capability to facilitate the differentiation of the osteoclastic and osteoblastic cells, which are responsible for the bone remodeling process. The purpose of this study was to evaluate whether the low-level laser therapy can accelerate orthodontic tooth movement during en masse retraction.Method:The study was a split-mouth design. The experimental side was exposed to biostimulation using 810 nm gallium-aluminium-arsenide diode laser. A total of 10 irradiations for 10 s per site were given 5 on the buccal side and 5 on the palatal side of the tooth. The total energy density at each application was 10 J with an interappointment gap of 3 weeks. The retraction was carried using a constant force of 150 gm. A digital vernier caliper measurement was used to measure the distance between the contact points of the maxillary canine and second premolar on 1st and 84th day.Results:The rate of orthodontic tooth movement was faster on the experimental side, and the difference between the two sides was statistically significant (P < 0.014).Interpretation and Conclusion:It was concluded that biostimulation carried out using an 810 nm diode laser is capable of increasing the rate of extraction space closure. Hence, it is capable of increasing the rate of orthodontic tooth movement.

Dental arch changes in postretention in Class II division 1 extraction cases.

The purpose of this study is to evaluate the postretention stability of the dental arches in Class II division 1 patients treated with four bicuspid extractions and the edgewise technique. A digital caliper was used to analyze the dental casts from 29 Class II division 1 malocclusion patients with skeletal type II (14 males, 15 females; ages ranging from 10.2-18.0 years), treated with four bicuspid extractions and the edgewise technique. Intercanine width, intermolar width, arch length, irregularity index, overjet and overbite were evaluated at three times: pretreatment (T1), posttreatment (T2) and postretention (T3) (mean: 4.15 years). Student's t-tests were used to compare the pretreatment-posttreatment, posttreatment-postretention and pretreatment-postretention. Significance was determined at P<0.05. The results of the study are listed as: (1) The upper and lower intercanine widths significantly increased (P<0.05) between T1-T2 and decreased between T2-T3. However, no significant changes were observed between T1-T3; (2) The upper and lower intermolar widths significantly decreased (P<0.05) between T1-T2, between T2-T3 and between T1-T3, except for the upper intermolar width between T2-T3 which showed no significant change; (3) The upper and lower arch lengths significantly decreased (P<0.05) at posttreatment and postretention due to the closure of extraction spaces. Both the upper and lower arch lengths significantly decreased between T1-T2, T2-T3, and T1-T3, except for the upper arch length between T2-T3, which showed no significant change; (4) The irregularity index was significantly improved after treatment. However, there was a slight increase in incisor irregularity at postretention. At postretention, 75.86% of the patients had mild crowding, 20.68% had moderate crowding, 3.48% had severe crowding; (5) The overjet and overbite significantly decreased (P<0.05) between T1-T2 and increased between T2-T3. The changes in the dental arches were small at postretention with a tendency to return towards their original position. The overall stability of Class II division 1 extraction cases is relatively good.

EVALUATION OF MINI-IMPLANT ANCHORAGE SYSTEM FOR EN-MASSE RETRACTION OF MAXILLARY ANTERIOR TEETH VERSUS CONVENTIONAL METHOD

Objectives: The purpose of this study was to compare the skeletodental and soft tissue changes and the duration needed for closure of extraction space after en-masse retraction of maxillary anterior teeth using mini-implant anchorage system in the treatment of maxillary dentoalveolar protrusion cases compared with two step retraction with conventional method of anchorage reinforcement. Materials and Methods: The study sample consisted of twenty adult orthodontic patients (3 males and 17 females) with maxillary dentoalveolar protrusion and required first premolar extraction and maximum anchorage. They were randomly divided into two treatment groups (10 subjects in each group). Group 1, anterior space closure with en-masse retraction aided by mini- implant anchorage system, or group 2, anterior space closure with two-step retraction technique aided by conventional method of anchorage. Lateral cephalometric head films were taken just before retraction of maxillary anterior teeth and immediately after closure of the extraction space for the evaluation of the treatment changes. Statistical analyses of the data were performed at a significance level of P <0.05. Results: For the skeletal parameters, a statistically significant decrease in the facial vertical dimensions was seen in G1, but the variables in G2 showed no significant differences (P > 0.05). Anchorage loss, in both the horizontal and vertical directions, was noted in G2, whereas G1 showed anchorage gain and intrusion of molars. Group 1 had greater anterior tooth retraction (7.8 mm in 9.6 months) than did the conventional anchorage group (5.5 mm in 12.4 months). However, no significant differences in the mean retraction time were noted between the 2 groups. Upper incisors were intruded in G 1 (2.3 mm) and extruded (1.1 mm) in G 2. The soft-tissue response was greater changes in G1 with significant differences were found in the nasolabial angle and amount of upper lip retraction between the groups (P < 0.05). Conclusion: Mini-implants provided absolute anchorage to allow greater skeletal, dental, and esthetic changes in patients requiring maximum anterior retraction, when compared with other conventional methods of anchorage reinforcement. However no differences in the mean retraction time were noted between the 2 groups.

Comparison of Anchorage Pattern under Two Types of Orthodontic Mini- Implant Loading During Retraction in Type A Anchorage Cases.

The orthodontic mini-screws are the mainstay of direct skeletal anchorage which requires minimal compliance and provides maximal anchorage control. However, the timing of initiation of orthodontic loading of these mini-screws is not clearly established in the available studies. The purpose of this study was to determine the reciprocal effects on mini-screw implant with immediate loading in comparison to that of delayed loading during retraction. The prospective clinical study included a sample of 25 orthodontic patients in the age range of 18-25 years. All the cases were of bi-maxillary proclination with Type-A anchorage demands. All the first premolars were indicated for extraction. A split mouth technique for each patient was utilized by loading mini-implant immediately after its placement on one side and the opposite side implant was loaded after a time lag of two weeks post-insertion. Retraction force of 150g was applied for three months on each side. The displacement of the head and tail of the implant, molar anterior tooth retraction was measured on Orthopantomograph (OPG) taken at T1 (initial) and T2 (after three months). A grid method with each 1mm magnified to 500 pixels was superimposed on OPG and the relative displacements were evaluated. Student's unpaired 't' test was used for comparison between left and right side and paired 't' test for the parameters on the same side. The p-value equal to or less than 0.05 was taken as statistically significant. The mean displacement of head of the implant on the immediate loading is 0.57mm where as the tail exhibited 0.75 mm. The head and tail of the implant on the delayed loading displaced by 0.35mm and 0.38mm respectively, on an average when data was analysed. Significant difference between the two types of loading was noted. Delayed loading is beneficial as compared to immediate loading during extraction space closure.

The Effect of Using Self-ligating Brackets on Maxillary Canine Retraction: A Split-mouth Design Randomized Controlled Trial.

The results of previous studies about the efficacy of using self-ligating brackets (SLBs) in controlling canine movement during retraction are not in harmony. Therefore, the current study aimed to compare the effects of using new passive SLBs on maxillary canine retraction with sliding mechanics vs conventional ligating brackets (CLBs) tied with metal ligatures. The sample comprised 15 adult patients (4 males, 11 females; 18-24 years) requiring bilateral extraction of maxillary first premolars. Units of randomization are the left or right maxillary canines within the same patient. The two maxillary canines in each patient were randomly assigned to one of the two groups in a simple split-mouth design. The canines in the SLBs group (n = 15) were bracketed with SLBs (Damon Q™), while the canines in the CLBs group (n = 15) were bracketed with conventional brackets (Mini Master Series). Transpalatal bars were used for anchorage. After leveling and alignment, 0.019 × 0.025" stainless steel working archwires were placed. Canines were retracted using a nickel-titanium close-coil springs with a 150 gm force. The amount and rate of maxillary canine retraction, canine rotation, and loss of anchorage were measured on study models collected at the beginning of canine retraction (T0) and 12 weeks later (T1). Differences were analyzed using paired-samples t-tests. The effect differences were statistically significant (p < 0.001). Using Damon Q™ SLBs, the amount and rate of canine retraction were greater, while canine rotation and anchorage loss were less. From a clinical perspective, extraction space closure can be accomplished more effectively using SLBs. Self-ligating brackets gave better results compared to the CLBs in terms of rate of movement, amount of canine rotation following extraction, and anchorage loss.

Class III orthognathic surgical cases facilitated by accelerated osteogenic orthodontics: a preliminary report

Abstract Objectives To describe a multidisciplinary treatment approach that includes corticotomy, orthodontic force and orthognathic surgery for the management of skeletal Class III surgical cases. The main advantage of the combined techniques is a reduction in treatment time for young adult patients. Method Accelerated Osteogenic Orthodontics (AOO) was delivered to three young adult patients during their pre-surgical orthodontic treatment. After aligning and levelling the dental arches, a piezosurgicalcorticotomy was performed to the buccal aspect of the alveolar bone. Bone graft materials were used to cover the decorticated area and soft tissue flaps were replaced. Results The mean time for extraction space closure was 5.4 ± 1.3 months and the mean time for pre-surgical orthodontic treatment was 12.0 ± 0.9 months. The average total treatment time was 20.4 ± 2.4 months. A pre-existing bony fenestration in the buccal cortex adjacent to the right lateral incisor root apex of Case 1 was corrected. Conclusion The facial aesthetics of three patients improved following multidisciplinary treatment. This approach may be an efficient method for the orthognathic patient who desires a reduced treatment time, but further clinical research is required.

A pilot clinical study of Class III surgical patients facilitated by improved accelerated osteogenic orthodontic treatments

To evaluate if the improved accelerated osteogenic orthodontics (IAOO) procedure could speed Class III surgical patients' preoperative orthodontic treatment duration and, if yes, to what extent. This study was also designed to determine whether or not an IAOO procedure affects the tooth-moving pattern during extraction space closure. The samples in this study consisted of 24 Class III surgical patients. Twelve skeletal Class III surgery patients served as an experimental group (group 1) and the others as a control group (group 2). Before treatment, the maxillary first premolars were removed. For group 1, after the maxillary dental arch was aligned and leveled (T2), IAOO procedures were performed in the maxillary alveolar bone. Except for this IAOO procedure in group 1, all 24 patients experienced similar combined orthodontic and orthognathic treatment. Study casts of the maxillary dentitions were made before orthodontic treatment (T1) and after extraction space closure (T3). All of the casts were laser scanned, and the amount of movement of the maxillary central incisor, canine, and first molar, as well as arch widths, were digitally measured and analyzed by using the three-dimensional model superimposition method. The time durations T3-T2 were significantly reduced in group 1 by 8.65 ± 2.67 months and for T3-T1 were reduced by 6.39 ± 2.00 months (P < .001). Meanwhile, the tooth movement rates were all higher in group 1 (P < .05). There were no significant differences in the amount of teeth movement in the sagittal, vertical, and transverse dimensions between the two groups (P > .05). The IAOO can reduce the surgical orthodontic treatment time for the skeletal Class III surgical patient by more than half a year on average. The IAOO procedures do not save anchorage.

Alveolar bone thickness and root length changes in the treatment of skeletal Class III patients facilitated by improved corticotomy: a cone-beam CT analysis

To evaluate the alveolar bone thickness and root length changes of anterior teeth with cone-beam computed tomography (CBCT). CBCT scans were taken for 12 skeletal Class III patients who accepted the improved corticotomy (IC) procedures during pre-surgical orthodontics. The CBCT data in T1 (the maxillary dental arch was aligned and leveled) and T2 (extraction space closure) were superimposed and the alveolar bone thickness at root apex level and root length measurements were done. From T1 to T2, the buccal alveolar bone thickness for the upper lateral incisors increased from (1.89±0.83) to (2.47±1.02) mm (P<0.05), and for central incisors and for canines from (2.32±0.71) to (2.68±1.48) mm and from (2.28±1.08) to (2.41±1.40) mm, respectively. According to Sharpe Grading System, the root resorption grade for 69 teeth of 72 was located in Grade 1, two teeth in Grade 2, one tooth in Grade 3. The improved corticotomy had the potential to increase the buccal alveolar bone thickness and the root resorption in most teeth was in Grade 1 according to Sharpe grading system.

Microimplant assisted extraction space closure: Biomechanical considerations

Implants have revolutionized the field of orthodontics by providing infinite or absolute anchorage. This new treatment approach has widened the therapeutic possibilities of orthodontic treatment. The science of biomechanics remains a mainstay of clinical orthodontics. The biomechanical variations with force application are significant when comparing conventional and mini-implant orthodontics. In order to fully exploit the potential of mini-implants, adequate knowledge of biomechanical principles and their modification in relation to mini-implants is imperative. This case report presents extraction space closure with temporary anchorage devices and describes biomechanical variations required in different clinical scenarios.

Effect of 810 nm Diode Laser Therapy on the Rate of Extraction Space Closure

Effect of 810 nm Diode Laser Therapy on the Rate of Extraction Space Closure

Comparative assessment of alignment efficiency and space closure of active and passive self-ligating vs conventional appliances in adolescents: A single-center randomized controlled trial

The aim of this study was to compare the time to initial alignment and extraction space closure using conventional brackets and active and passive self-ligating brackets. One hundred adolescent patients 11 to 18 years of age undergoing maxillary and mandibular fixed appliance therapy after the extraction of 4 premolars were randomized with stratification of 2 age ranges (11-14 and 15-18 years) and 3 maxillomandibular plane angles (high, medium, and low) with an allocation ratio of 1:2:2. Restrictions were applied using a block size of 10. Allocation was to 1 of 3 treatment groups: conventional brackets, active self-ligating, or passive self-ligating brackets. All subjects were treated with the same archwire sequence and space-closing mechanics in a district general hospital setting. The trial was a 3-arm parallel design. Labial-segment alignment and space closure were measured on study models taken every 12 weeks throughout treatment. All measurements were made by 1 operator who was blinded to bracket type. The patients and other operators were not blinded to bracket type during treatment. Ninety-eight patients were followed to completion of treatment (conventional, n = 20; active self-ligating brackets, n = 37; passive self-ligating brackets, n = 41). The data were analyzed using linear mixed models and demonstrated a significant effect of bracket type on the time to initial alignment (P = 0.001), which was shorter with the conventional brackets than either of the self-ligating brackets. Sidak's adjustment showed no significant difference in effect size (the difference in average response in millimeters) between the active and passive self-ligating brackets (the results are presented as effect size, 95% confidence intervals, probabilities, and intraclass correlation coefficients) (-0.42 [-1.32, 0.48], 0.600, 0.15), but the conventional bracket was significantly different from both of these (-1.98 [-3.19, -0.76], 0.001, 0.15; and -1.56 [-2.79, -0.32], 0.001, 0.15). There was no statistically significant difference between any of the 3 bracket types with respect to space closure. Space-closure times were shorter in the mandible, except for the Damon 3MX bracket (Ormco, Orange, Calif), where active and total space-closure times were shorter in the maxilla. No adverse events were recorded in the trial. Time to initial alignment was significantly shorter for the conventional bracket than for either the active or passive self-ligating brackets. There was no statistically significant difference in passive, active, or total space-closure times among the 3 brackets under investigation.

A comparative in-vivo evaluation of the alignment efficiency of 5 ligation methods: A prospective randomized clinical trial.

Objectives:To conduct a prospective randomized study comparing the efficiency of 5 different ligation systems (ELL; elastomeric ligature, SSL; stainless steel ligature, LL; leone slide ligature, PSL; passive self-ligation and ASL; active self-ligation) over the duration of mandibular crowding alleviation.Materials and Methods:Fifty consecutive patients (54.2% male, 45.8% female; mean age: 16.69 years) satisfying the inclusion criteria were randomly allocated to 5 ligation groups with an equal sample size of 10 per group. The 5 groups received treatment with 0.022-inch MBT pre-adjusted edge-wise technique (ELL: Gemini 3M Unitek, SSL: Gemini 3M Unitek, LL: Gemini 3M Unitek, PSL: SmartClip 3M Unitek and ASL: In-Ovation R Euro GAC International). The models and cephalograms were evaluated for anterior arch alignment, extraction space closure, and lower incisal inclinations at pre-treatment T1 and at the end of initial alignment T2. Analysis of variance (ANOVA) and Post-hoc tests were used for data analysis.Results:Forty-eight participants completed the study, and SL systems showed a significant difference over CL groups in time to alignment, passive space closure, and incisal inclination. Multiple regression showed a reduction of 5.28 days in time to alignment by changing the ligation group in the order of ELL to ASL group and 1 mm increase in initial irregularity index increases time to alignment by 11.68 days.Conclusion:Self-ligation brackets were more efficient than conventional ligation brackets during initial leveling and alignment.

Ridge preservation with synthetic nanocrystalline hydroxyapatite reduces the severity of gingival invaginations—a prospective clinical study

Gingival invaginations develop after tooth extraction and subsequent orthodontic space closure. Aetiological factors and long-term effects of gingival invaginations on oral health are nearly unknown. In addition, preventive or therapeutic strategies are rare. This prospective clinical study employing the split mouth technique was performed to investigate the effect of extraction socket augmentation with a synthetic nanocrystalline hydroxyapatite (NanoBone(®) Artoss, Rostock, Germany) on the incidence and degree of gingival invaginations. A total of 10 orthodontic patients with need for symmetric premolar extractions offering a total of 28 extractions were included in this trial. The study plan provided one extraction site to be augmented with synthetic nanocrystalline hydroxyapatite (NanoBone(®)), the other served as control. After primary wound healing, space closure was performed under defined biomechanical conditions. After space closure was accomplished, occurrence and degree of gingival invaginations as well as probing depths of the adjacent teeth mesial and distal to the extractions were determined and dental radiographs were taken. The degree of gingival invaginations and probing depths mesial and distal of the extraction were significantly reduced on NanoBone(®) augmented extraction sites. In addition, 70% of the radiographs revealed translucent and hyperdense areas on the intervention side after space closure. Apical root resorption was found in 2 patients on both the NanoBone(®) side and the control side. Ridge preservation with NanoBone(®) appeared to reduce the severity of gingival invaginations. Further investigation on long-term effects is mandatory to eliminate the appearance of adverse effects.