Orthodontic Research Articles

Autotransplantation combined with orthodontic treatment: 7 year follow-up

Autotransplantation combined with orthodontic treatment: 7 year follow-up

Comparison of Intercanine and Intermolar Width Between Cleft Lip Palate and Normal Class I Occlusion Group.

To determine the mean difference of arch dimensions (both intercanine and intermolar width) between cleft lip palate and normal class I occlusion group. Cross-sectional analytic study. Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, [Dow University of Health Sciences (DUHS)], Karachi, from March 2012 to April 2013. Group 1 consisted of 32 subjects with complete repaired, non-syndromic unilateral and bilateral cleft lip palate. Group 2 consisted of 32 subjects with normal facial morphology and class I occlusion. Exclusion criteria were cleft lip palate subjects with systemic diseases, any arch expansion procedure, incomplete repaired palate, open fistulas, developmental or acquired craniofacial muscular deformities, autoimmune conditions, syndromes, endocrine abnormalities, neurological problems, or previous history of orthodontic treatment and signs and symptoms of temporomandibular disorders, history of trauma, impacted or missing teeth, periodontally involved teeth, subdivision molar classification, skeletal base II and III with molar class I. The transverse width (intercanine and intermolar width) of dental casts was measured with the help of digital caliper. The intercanine width was measured between cusp tips of the canine while the intermolar width distance was measured between mesiobuccal cusp tips of first molars, and buccal grooves of the mandibular first molars in both cleft lip palate and normal class I occlusion group, respectively. There were 64 subjects with mean 14.7 ±6.8 years in the cleft palate and 14.7 ±6.3 years in the normal group. There was statistically significant differences found between intercanine and intermolar width in maxillary arch (p < 0.001). In mandibular arch, only intercanine width has showed significant difference (p < 0.001) between cleft and normal occlusion class I group. Maxillary and mandibular intercanine width was found to be significantly reduced in cleft lip palate group (both unilateral and bilateral) as compared to normal class I occlusion group.

Clinical application of padded molars during orthodontic treatment

Objective To investigate the clinical application value of padded molars. Methods Totally 54 cases of malocclusions from Department of Orthodontics of West China Hospital of Stomatology were received occlusal pads by optiband ultra band bongding at the early stage of orthodontic treatment (1th-5thmonth). The lateral cephalometric radiographs before and after treatments were analyzed. The effects on vertical height of molars after using padded molars were observed. Results The padded molars did not affect the vertical height without statistical difference (P>0.05). Conclusions Temporary using padded molars were feasible in orthodontic treatment. Padded molars may be widely applied in clinical orthodontics. Key words: Molar/SU; Orthodontics, corrective; Malocclusion/SU

Optimum force magnitude for orthodontic tooth movement: a systematic literature review.

The aim of this study was to perform a meta-analysis of the literature concerning the optimal force or range of forces for orthodontic tooth movement. Over 400 articles both on human research and animal experiments were found in Medline and by hand searching of main orthodontic and dental journals. Articles on animal experiments were in the majority. A wide range of animal species such as rat, cat, rabbit, beagle dog, monkey, mouse, and guinea pig were used. Besides variation in species, there was also a wide range of force magnitudes, teeth under study, directions of tooth movement, duration of experimental period, and force reactivation. Furthermore, hardly any experiments were reported that provide information on the relation between the velocity of tooth movement and the magnitude of the applied force. Data from human research on the efficiency of orthodontic tooth movement appeared to be very limited. The large variation in data from current literature made it impossible to perform a meta-analysis. Therefore, we have systematically reviewed the literature. It appeared that no evidence about the optimal force level in orthodontics could be extracted from literature. Well-controlled clinical studies and more standardized animal experiments in the orthodontic field are required to provide more insight into the relation between the applied force and the rate of tooth movement.

Improvement of cheek retractor for clinical dental photograph of dental profession

Objective To measure Chinese occlusion cast and skull lateral projection to acquired height, depth and arch of normotopia and lateral position, so as to obtain the data of national people for improvement of dental retracter and enhancing photography quality. Methods From May 2008 to May 2010 in Department of Orthodontics Peking University School and Hospital of Stomatology, a total of 247 cases were selected by convenient sampling method. The patients selected completed nonextraction treatment and had all permanent teeth without loss of tooth and second accessional teeth dentia already, and their molar relationship was neutral, and their overbite and overlap were normal. After treatment, we ensured fang′s point, molar point, subspinable, supramentale, maxillary second molar distal to the surface profile and mandibular second molar distal to the neck point by deposit model and skull lateral projection. The dental retracter height and depth of normotopia and lateral position, and we compared the measurement values of dental retracter between existed retracter and retracter model by X-ray. Results The model and X-ray measured depth of normotopia and lateral position, which were (39.54±4.29) mm and (36.18±3.26) mm compared with a similar size 39.20 mm and 34.41mm of existed retracter (P>0.05). The model and X-ray measured the height of model′s normotopi, which was (12.41±2.67) mm and was smaller than 16.13 mm of existed one (P<0.01); the model and X-ray measured the height of lateral position, which was (39.54±4.29) mm and bigger than the existed one (31.16 mm) (P<0.01). Conclusions The national dental retracter depth of normotopia and height of lateral position are discrepant with existed dental retracter, so it requires to design material retracter for clinical use, and compare with traditional retracter′s surface of image to find out the shortages and improve. Key words: Orthodontics; Retractor; Medical photography

Interleukin-17 expression induced by orthodontic force in periodontal ligament in different periodontal condition

To investigate interleukin (IL)-17 expression induced by orthodontic force in periodontal ligament under different periodontal conditions. Seventy-seven male SD rats were divided randomly into 5 groups: healthy movement group (HM), active periodontitis movement group (PM) recovery periodontitis movement group (RM), positive control group (PC) and normal control group (NC). Active periodontitis was set up by means of ligature + susceptible bacteria + suger water in PM, PC and RM groups. This stimulating factor was removed in RM group. NiTi spring was used to apply 0.49 N mesial force to move upper first molar of the rats in HM, PM and RM groups. HM, PM and RM group rats were sacrificed on day 3 (d3), day 7 (d7) and day 14 (d14). Expression changes of IL-17 in periodontal tissue in each group were measured using immunohistochemical stain and real time fluorescence quantitative PCR. IL-17 expression in periodontal ligament showed more positively in PM and RM groups compared with NC, PC and HM groups. No difference was found in the expression of IL-17 mRNA in NC (1.00 ± 0.00) (P > 0.05), except in HM d14 (1.00 ± 0.07) and RM d14 (1.19 ± 0.15). Higher expression of IL-17 mRNA (P < 0.05) was found in other groups. The expression of IL-17 mRNA in RM d3 and d7 increased more than that in HM group in the same period (P < 0.05) and it decreased significantly (P < 0.05) compared with that in PM groups in the same period. IL-17 was involved in the regulation of orthodontic tooth movement in different periodontal conditions. Orthodontic force caused limited increase of IL-17 mRNA expression in recovery phase of periodontitis at early stage, then back to normal. However, in active inflammatory periodontal tissue, orthodontic force kept IL-17 mRNA at high level.

Bone and Calcium Metabolisms Associated with Dental and Oral-Maxillofacial Diseases. Orthodontic treatment and the role of osteocytes

Tooth movement accompanies the active morphological changes of the alveolar bone that was applied mechanical force via teeth. Coordination of initial changes of periodontal membrane and subsequent bone remodeling produce dramatic tooth alignment. It is well known small bone cells support this dynamic change of tooth movement. Especially, osteocytes are thought to be mechanosensor cells in bone remodeling. This review focuses on the bone remodeling during tooth movement as well as molecular events of osteocytes in RANKL/RANK/OPG pathway. In addition, dynamics of DMP-1, MEPE and Sclerostin during orthodontic tooth movement are discussed with published literature.

A pilot study of root position in orthodontic diagnosis model set-up

To investigate the importance of root information in diagnosis set-up by constructing three-dimensional (3D) digital models with individual anatomic roots. Pretreatment cone-beam CT (CBCT) and laser scanning data were collected from two patients (extraction and non-extraction each) with skeletal Class I malocclusion. Threshold segmentation of the CBCT was performed to generate a 3D digital model which has individually isolated tooth. This model and the scan model were superimposed to generate an integrated model (Mo) composed of high-resolution surface scan crowns sutured to the CBCT roots. Pretreatment dentition plaster model were made into set-up model. The diagnosis model set-up was performed successively by three orthodontists and one senior orthodontic technician. Set-up model scan of each patient after tooth alignment was obtained. The isolated composite teeth were individually superimposed onto the set-up model surface scan to creat set-up model (Ma, Mb, Mc, Md) containing root position. These isolated composite teeth were also superimposed onto the posttreatment surface scan depicting the posttreatment model (M). In order to observe whether diagnosis model set-up would cause exposure of the root, Ma-Md were compared with Mo, which showed the true positions of alveolus. In order to validate the accuracy of the expected root position setup, Ma-Md were compared with the true root position represented by M. Color displacement maps generated to measure the discrepancies of root positions. Nonparallel and exposure of the root was found in all setup models. Color displacement maps through molar superimpositions showed maximum differences of 8.79 mm for the maxillary teeth and 9.96 mm for the mandibular teeth. Diagnosis model set-up based only on crown can not absolutely ensure the good alignment of roots without root exposure. It is necessary to construct the integrated model including root for diagnosis during tooth arrangement process.

Study on the difference of corresponding age at cervical vertebral maturation stages among different skeletal malocclusions

To compare the difference of corresponding age at cervical vertebral maturation (CVM) stages among different skeletal malocclusions and provide clinic guideline on optimal treatment timing for skeletal malocclusion. Based on ANB angle, 2 575 cephalograms collected from Department of Orthodontics, Peking University School and Hospital of Stomatology from May, 2006 to November, 2014 were classified into skeletal Class I (ANB 0°~5°, 1 317 subjects), Class II (ANB > 5°, 685 subjects) and Class III (ANB < 0°, 573 subjects) groups. CVM stages were evaluated with the modified version of CVM method. Independent sample t test was performed to analyze the difference of age at different CVM stages among various skeletal groups. Significant gender difference of age was found at CS3 to CS6 for skeletal Class I group (P < 0.05), at CS5 and CS6 for skeletal Class II group (P < 0.05), and at CS3 and CS5 for skeletal Class III group (P < 0.05). At CS3 stage, the average age of male in skeletal Class II and skeletal Class III groups was (11.6 ± 1.5) years old and (10.3 ± 1.9) years old, respectively; the average age of females in those two groups was (11.7 ± 1.3) years old and (9.3 ± 1.5) years old, respectively, and significant difference was found in both comparisons (P < 0.05). Compared average age at CS5 and CS6 between skeletal Class II and skeletal Class III groups [the ages of male was (15.1 ± 1.7) and (16.8 ± 1.6) years old, the ages of male was (14.6 ± 1.2) and (15.7 ± 2.5) years old], significant difference was also found (P < 0.05). Significant gender differences were found when evaluated CVM stage and age in skeletal Class I, II and III groups. Significant differences of age at different CVM stage was noted when skeletal Class II was compared with skeletal Class III groups.

Bond strength of direct and indirect bonded brackets after thermocycling.

Thermocycling simulates the temperature dynamics in the oral environment. With direct bonding, thermocycling reduces the bond strength of orthodontic adhesives to tooth structure. The purpose of this study was to evaluate the shear bond strengths (SBS) of one direct and two indirect bonding methods/adhesives after thermocycling. Sixty human premolars were divided into three groups. Teeth in group 1 were bonded directly with Transbond XT. Teeth in group 2 were indirect bonded with Transbond XT/Sondhi Rapid Set, which is chemically cured. Teeth in group 3 were indirect bonded with Enlight LV/Orthosolo and light cured. Each sample was thermocycled between 5 degrees C and 55 degrees C for 500 cycles. Mean SBS in groups 1, 2, and 3 were not statistically significantly different (13.6 +/- 2.9, 12.3 +/- 3.0, and 11.6 +/- 3.2 MPa, respectively; P > .05). However, when these values were compared with the results of a previous study using the same protocol, but without thermocycling, the SBS was reduced significantly (P = .001). Weibull analysis further showed that group 3 had the lowest bonding survival rate at the minimum clinically acceptable bond-strength range. The Adhesive Remnant Index was also determined, and group 2 had a significantly (P < .05) higher percentage of bond failures at the resin/enamel interface.

Porcelain surface roughness, color and gloss changes after orthodontic bonding.

The purpose of this study was to evaluate the alteration in surface characteristics after orthodontic debonding of two types of porcelain systems commonly used in prosthetic dentistry. For this purpose, porcelain specimens were fabricated from low-fusing (n = 20) and high-fusing (n = 20) porcelain. The baseline surface roughness, color, and gloss were evaluated using profilometry, color shade index, and gloss study. All specimens were bonded with brackets and debonded using a testing machine at a rate of 0.1 mm/minute crosshead speed. The porcelain surfaces were polished using a 12-fluted carbide composite removal bur (low-fusing, n = 20; high-fusing, n = 20). In addition, half of each porcelain group was further polished using a series of Sof-Lex discs (low-fusing, n = 10; high-fusing, n = 10). The postdebond porcelain surface characteristics roughness, color, and gloss were reevaluated and compared with baseline measurements. The results were analyzed with two-way analysis of variance and Tukey multiple comparisons test, with porcelain type (low-fusing or high-fusing) and polishing protocol (carbide bur or carbide bur and discs) serving as discriminate variables at alpha = 0.05 level of significance. Bonding and debonding increased all roughness parameters tested; however, no change was revealed between the two polishing protocols. Similarly, gloss and color index changes were significantly altered after resin grinding, regardless of the polishing method used. No difference was identified between the two porcelain types with respect to roughness, color index, or gloss. Orthodontic bonding alters the porcelain surfaces, and postdebond polishing does not restore the surface to the prebond state.

A comparison of bond strength between direct- and indirect-bonding methods.

The purpose of this study was to evaluate and compare the shear bond strength and the sites of bond failure for brackets bonded to teeth, using two indirect-bonding material protocols and a direct-bonding technique. Sixty extracted human premolars were collected and randomly divided into three groups. The direct-bonded group (group 1) used a light-cured adhesive and primer (Transbond XT). One indirect-bonded group (group 2) consisted of a chemical-cured primer (Sondhi Rapid Set) and light-cured adhesive (Transbond XT), whereas the other group (group 3) used a light-cured primer (Orthosolo) and adhesive (Enlight LV). Forty hours after bonding, the samples were debonded. Mean shear bond strengths were 16.27, 13.83, and 14.76 MPa for groups 1, 2, and 3, respectively. A one-way analysis of variance showed no significant difference in mean bond strength between groups (P = .21). Furthermore, a Weibull analysis showed all three groups tested provided over a 90% survival rate at normal masticatory and orthodontic force levels. For each tooth, an Adhesive Remnant Index (ARI) score was determined. Group 2 was found to have a significantly lower ARI score (P < .05) compared with groups 1 and 3. In addition, Pearson correlation coefficients indicated no strong correlation between bond strength and ARI score within or across all groups.

Index assessment of the hygienic condition of the mouth and periodontal tissues in orthodontic patients with chronic hypertrophic gingivitis during treatment with braces technics

Обстежено 126 пацієнтів віком від 16 до 35 років, у яких на тлі проведеного лікування незнімною ортодонтичною апаратурою розвинувся хронічний гіпертрофічний гінгівіт. Із метою об’єктивної оцінки стану тканин пародонта проведено визначення гігієнічних та пародонтальних індексів. Виявлено суттєві порушення з боку кількісних і якісних показників, які характеризують стан гігієни ротової порожнини та ступінь запалення пародонта у хворих на хронічний гіпертрофічний гінгівіт до початку лікування. Відмічено статистично достовірні зміни досліджуваних індексів у пацієнтів із І та ІІ ступенем тяжкості хвороби порівняно з показниками норми, але вірогідно вираженіші – при ІІ ступені. Отримані результати дозволяють стверджувати, що при ортодонтичному лікуванні брекет-технікою спостерігається прогресуюче погіршення гігієни ротової порожнини, що тісно пов’язано з наростанням запалення в тканинах пародонта.

Allogenic banking of dental pulp stem cells for innovative therapeutics.

Medical research in regenerative medicine and cell-based therapy has brought encouraging perspectives for the use of stem cells in clinical trials. Multiple types of stem cells, from progenitors to pluripotent stem cells, have been investigated. Among these, dental pulp stem cells (DPSCs) are mesenchymal multipotent cells coming from the dental pulp, which is the soft tissue within teeth. They represent an interesting adult stem cell source because they are recovered in large amount in dental pulps with non-invasive techniques compared to other adult stem cell sources. DPSCs can be obtained from discarded teeth, especially wisdom teeth extracted for orthodontic reasons. To shift from promising preclinical results to therapeutic applications to human, DPSCs must be prepared in clinical grade lots and transformed into advanced therapy medicinal products (ATMP). As the production of patient-specific stem cells is costly and time-consuming, allogenic biobanking of clinical grade human leukocyte antigen (HLA)-typed DPSC lines provides efficient innovative therapeutic products. DPSC biobanks represent industrial and therapeutic innovations by using discarded biological tissues (dental pulps) as a source of mesenchymal stem cells to produce and store, in good manufacturing practice (GMP) conditions, DPSC therapeutic batches. In this review, we discuss about the challenges to transfer biological samples from a donor to HLA-typed DPSC therapeutic lots, following regulations, GMP guidelines and ethical principles. We also present some clinical applications, for which there is no efficient therapeutics so far, but that DPSCs-based ATMP could potentially treat.

Orthodontic treatment of patients with mandibular incisor extraction

Objective To evaluate the indications and effectiveness of lower incisor extraction in orthodontics. Methods Twenty-three adult patients with lower incisor extraction were included in the study. The cases consisted of 14 female and 9 male patients with an average age of 23.2 years at the start. One single lower incisor was extracted in 17 patients and the other tow upper premolars were extracted in 6 patients. Cephalometric and casts analyses were carried out. Results Total treatment time was 13-23 months. All extraction space was closed after the treatment. All patients achieved satisfactory treatment results, with normal overbite and overjet and stable occlusal relationship. There were no significant changes before and after treatment on cephalometric analysis. The intercanine width was reduced by from pretreatment to posttreatment [(26.89±2.89) mm vs (23.92±1.54) mm (P<0.05)]. Conclusions The intercanine width is reduced after lower incisor extraction. In order to achieve satisfactory clinical effect, we should carefully select cases and pay attention to the corresponding techniques and methods. Key words: Mandibular incisor; Extraction; Orthodontics

The role of CBL combined with network teaching method in clinical ability training of orthodontic postgraduate students

Objective To study the effects of case-based learning (CBL) teaching method combined with network on orthodontic postgraduate clinical ability training. Methods Totally 40 orthodontic postgraduates were randomly divided into 2 groups (20 per group) named as experimental group (EG) and control group (CG). EG involved in CBL combined with network teaching method, while CG with CBL method only. after 5 teaching cycles, test scores of two groups were analyzed with SPSS 22.0. Results Average scores were (86.60±9.71) in EG and (85.45±10.79) in CG, without statistical differences (P=0.73). Pass rate of two groups were 95.00% and 90.00%, without statistical differences (P=1.00); As for the questionnaire survey, most of the students (90.00%) in EG considered CBL combined with network teaching method had no confliction with the clinical time, and helped to carry out in-depth clinical topic discussion. What was more, all of them (100.00%) in EG believed network facilitate their learning. Only part of them (60.00%) in EG thought that they spent a lot of time on reference material preparation. Conclusions Both CBL combined with network teaching method and CBL method can improve the clinical ability of orthodontic postgraduates significantly. However, CBL combined with network teaching method has advantages over time management, knowledge learning and resource sharing. Key words: Case-based learning; Network teaching method; Postgraduate training; Orthodontic

Comparison of influence of resin core on overall bending strength of fiber post-core restoration

Objective To compare the influence of resin core on overall bending strength of fiber post-core restoration. Methods 60 mandibular first premolar extracted because of orthodontic treatment was selected.3M light -cured composite resin P60,medental dual-cured resin,pulpdent dual-cured resin combined with viva carbon fiber reinforced glass fiber post were applied.The changes of teeth in vitro were observed when strength was given on. Results The flexural strength of 3M light-cured composite resin was(80.182±9.512)N,Medental dual-cured resin was(87.805±11.649)N,Pulpdent dual-cured resin was(85.458±10.845)N.The flexural strength of 3M lightcured composite resin was lower than that of medental dual-cured resin and pulpdent dual-cured resin(t=5.758,3.084,both P 0.05). There was large area of resin broken off after 3M light-cured composite resin core fracture.There was only fracture of medental dual-cured resin core and pulpdent dual-cured resin core. Conclusion The bending strength of dual-cured resin is better than that of highly filled light curing composite resin in large tooth hard tissue defect restoration with fiber post-core, and core broken off is rare. Dual-cured resin is better post-core materials. Key words: Fiber post; Post core crown restoration; Dual-cured resin; Light curing composite resin; Bending strength

Clinical effect of orthodontic treatment in patients with bilateral cleft palate and erupted canine before alveolar bone graft

Objective To study the clinical effect of orthodontic treatment in patients with bilateral completely cleft palate and completely erupted canines before alveolar bone graft. Methods Patients were divided into two groups: test group included patients with bilateral completely cleft palate and completely erupted canines; and control group included patients with bilateral cleft palate whose canine had not erupted. Orthodontic treatment was performed before surgical bone graft operation. X-ray morphometry was performed 6 months after surgical procedure. Bergland standard was used to estimate the clinical effect of bone graft. TypesⅠand Ⅱ were considered as success and Types Ⅲ and Ⅳ as failure. X-ray analysis was performed in each patient. Results The test group included 25 patients and control group 56 patients. The number of TypesⅠand Ⅱ in the test group was 20, with successful rate of 80%. The number of Types Ⅰ and Ⅱ in control group was 53, with successful rate of 94.6%. There was a statistical difference between two groups (P<0.05). In the test group, the number of TypeⅠ was 12, about 60% of all successful cases. In control group, the number of TypeⅠ was 48, about 90.6% of all successful cases. There was significantly statistical difference between two groups (P<0.01). In the test group, the number of Type Ⅳ was 4, about 80% of all fail cases. In control group, no Type Ⅳ happened. There was also a statistical difference between two groups (P<0.05). Conclusions Orthodontic treatment and surgical bone graft can be done successfully in older patients with bilateral cleft palate and completely erupted canines. Key words: Bilateral cleft palate; Alveolar process; Orthodontic

Different maxillomandibular advancement methods for the treatment of severe obstructive sleep apneahypopnea syndrome

To review the outcomes of three different methods of maxillomandibular advancement for the treatment of severe obstructive sleep apnea-hypopnea syndrome (OSAHS). Twenty-four patients with severe OSAHS from January 2011 to January 2014 treated by three different methods of maxillomandibular advancement (MMA) and genioplasty, maxillomandibular advancement without rotation plus genioplasty, maxillomandibular advancement with counterclockwise rotation plus advancement genioplasty, maxillomandibular advancement with first premolars extraction and subapical osteotomy setback under general anesthesia were included in the study. Comparison of per-operative and post-operative cephalometric analysis, polysomnography (PSG), apnea and hypopea index (AHI), body mass index (BMI), average blood oxygen saturation (AOS), lowest oxygen saturation (LSaO2) and posterior airway space (PAS) data were performed. The operative time and post-surgical orthodontic treatment data were collected and analyzed. According to Stanford criteria, the success rate of 100% was achieved with all the three methods. The difference between per-operative and post-operative AHI, AOS, SNPg and PAS were statistically significant (P<0.0001) for all the three methods. Significant difference was found between per-operative and post-operative SNA (81.51°±3.36° vs 88.17°±4.51°, P<0.0001), (82.25°±2.71° vs 86.54°±3.65°, P=0.0002) and SNB (72.37°±3.99° vs 80.59°±3.40°, P<0.0001), (73.65°±3.80° vs 81.37°±2.96°, P<0.0001) among MMA without rotation plus genioplasty and MMA with counterclockwise rotation and advancement genioplasty respectively. However, no significant difference was found between the pre-operative and post-operative SNA (82.18°±4.27° vs 84.19°±2.70°, P=0.2015) and SNB (73.28°±3.04° vs 75.35°±2.56°, P=0.2640) among MMA with first premolars extraction and subapical osteotomy setback. The average duration of postoperative orthodontics treatment was 8.3 months. MMA and advancement genioplasty is an effective surgical management for severe OSAHS. Cephalometric analysis and computer aided design are needed for personalized surgical methods. MMA without rotation and advancement genioplasty method leads to the protrusive skeletal deformity. MMA with counterclockwise rotation and advancement genioplasty method is effective in curing severe OSAHS with little effect on facial profile. MMA with first premolars extraction and subapical osteotomy requires longer operative time and longer postoperative orthodontic treatment.

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.