Treatment Efficiency And Effectiveness:a Comparison Between Selt-ligating And Conventional Bracket Systems

Introduction: There are several reports of self-ligating brackets (SLBs) advantagesover conventional brackets (CBs). The said advantages of SLBs include greaterpatient comfort during treatment, better oral hygiene, increased patient cooperation,more certain archwire engagement, fewer visits to orthodontists, overall shortertreatment time, improved anchorage stability, less need for extractions, and betteroutcomes in term of occlusal and facial esthetics.The aim of this study was to compare the treatment efficiency and effectiveness ofconventional brackets and self-ligating Smart-Clip brackets.Methodology: The three specific objectives of this study, namely the archdimensional changes, the rate of incisors alignment and space closure were measuredprospectively among patients attending the orthodontic clinic of the Jilin UniversityCollege of Dental Medicine under controlled clinical trial design, while the totaltreatment time, anchorage loss and the incisors torque expression were measuredretrospectively on lateral cephalograms and cast models of patients treated between2007and2012.The study used three different sample groups to compare the clinical performance ofSLBs and CBs. Forty-five patients were included in measuring the arch dimensionalchanges and rate of incisors alignment, with the Little’s Irregularity Index being usedto quantify the incisors discrepancies before and after alignment. To assess the archdimensional changes, the vernier caliper (Dentaurum, Germany) was used to measurethe inter-canine and inter-molar distances on dental cast models before and afteralignment stage utilizing cusps and central grooves as reference points on canines andfirst molars respectively.Thirty-two participants were recruited for extraction space closure investigation. Allparticipants in SLB group used SmartClip (3M Unitek, Monrovia, Calif, USA), whilethe CB used Victory Series (3M Unitek, Monrovia, Calif, USA) both with0.022-inslot. After alignment, a0.019X0.025-in SS archwire were placed with hooksbetween lateral incisors and the canines. Nickel-titanium (Ni-Ti) medium Sentalloycoil springs (GAC, NY) were placed across the extraction sites from the molar band hook on the first molar; the springs were activated to200g and ligated with an SSligature to the archwire hook mesial to the canine. The extraction spaces (measuredbetween the closest points on the distal canine and mesial premolar proximal surfaces)measurements were done intra-orally by a vernier caliper (Dentaurum, Germany) onmonthly visits before force activation. The difference between the initial (R1) and thelast but one (R2) measurements was calculated to get the total amount of spaceclosure, and this was divided by the time taken (in months) to obtain the rate of spaceclosure in millimeters per month.The retrospective cohort study compared34patients SLB group treated by SmartClip(3M Unitek, Monrovia,Calif, USA) brackets to35patients CB group treated byconventional pre-adjusted brackets Victory series (3M Unitek, Monrovia, Calif, USA)ligated by stainless steel wire ligatures. Pre-treatmen (T1) and post-treatment (T2)lateral cephalograms were traced and analyzed by Pancherz sagittal-occlusion analysisto obtain skeletal and dental changes in the maxilla and the mandible. The dental castmodels were assessed by the Peer Assessment Rating (PAR) Index for the treatmentoutcomes.Results: This section displays the results obtained from three sample groups asdescribed in the materials and methods section. The samples included Forty-five non-extraction patients (14.02years mean age) for arch dimensional changes and rate ofincisors alignment assessment, thirty-two participants with15.6-years mean age forextraction space closure assessment; and sixty-nine patients (15.64years mean age) toexamine the treatment time, outcome, and anchorage loss. Further details on everysample results are described below:i) Arch dimensional changes and rate of incisors alignment assessmentThe mean total (maxillary and Mandibular) discrepancy reductions were6.66-mm(SLB) and8.04-mm (CB). Whereas, the time used for incisors alignment by SLB andCB groups were93.48-and93.38-days respectively. The occlusal dimensionalchanges and rate of Little’s index reduction between the SLB and CB groups were notstatistically significant. The mean Little’s index reduction (mm/month) was2.05forSLB and2.43for CB groups. The difference was not statistically significant (P=.216)ii) Extraction space closure assessment The overall rate of space closure between the SLB and CB groups was not statisticallysignificantly different (P=.70). Even the site specific (i.e. right/left side andupper/lower jaw) were not significantly different.iii) Treatment time, outcome, and anchorage lossThe mean treatment time for SLBs (19.19months) was not statistically significantlydifferent from21.25months of CBs; but the treatment time and pre-treatment PARscores were strongly correlated. There was no difference in anchorage loss betweenSLB and CB groups. There were significant dental and skeletal changes amongadolescent orthodontic patients regardless of the bracket used. The lingual inclinationof mandibular incisors in CBs was3.62°more than SLBs group (P <0.01).Conclusions: Based on the current study findings, the rate of space closure in en-masse mechanics and the time required for incisors alignment are independent of thebracket type. The total treatment time and anchorage loss are not influenced by thetype of bracket used. However, there are significant dental and skeletal changesamong adolescent orthodontic patients regardless of the bracket used. There lingualinclination of mandibular incisors is significantly greater in CBs than SLBs group.