Maxillary Incisor Retraction Research Articles

Anterior maxillary and mandibular subapical osteotomy for correction of bimaxillary protrusion

Bimaxillary protrusion (BP) is one of the most prevalent dentofacial deformities in the Asian population. Facial esthetics is the primary concern of these patients. Typical orthodontic treatment includes retraction of maxillary and mandibular incisors after extraction of the four first premolars, but this might not yield desired esthetic changes in the patient. Thus, orthognathic surgery such as anterior subapical osteotomies and extraction of premolars can be looked upon as an option to correct sagittal excess of the jaw bones and associated dental anomalies. This case report describes the treatment of a middle-aged woman with complaints of lip protrusion and unfavorable esthetics due to present malocclusion with the help of anterior maxillary and mandibular osteotomy procedure which provides a stable and viable treatment option for desired esthetic results.

The effect of platelet-rich fibrin (PRF) on maxillary incisor retraction rate.

To investigate the efficiency of platelet-rich fibrin (PRF) injection on maxillary incisor retraction rate. The study included 40 patients (23 women and 17 men; mean age; 20.7 ± 1.45) with Class II Division 1 malocclusion. The treatment plan for all patients was extraction of the maxillary first premolars and canine distalization, followed by retraction of the maxillary incisors. Patients were randomly divided into two groups. The study group received injectable platelet-rich fibrin (i-PRF) two times with an interval of 2 weeks; the control group did not receive i-PRF. In both groups, the measurements were bilaterally assessed as the distances between the lateral and canine teeth on the plaster models at five time points. The rate of incisor movement was evaluated by Student's t-test, analysis of variance, and Tukey honestly significant difference tests. Statistical significance was set as P < .05. The average movements of incisors were significantly higher in the study group than the control group at all time points (P < .05). According to the within-group comparison, none of the measurements showed any significant differences between the right and left sides in both groups at all time points (P > .05). While the movement of incisors was significantly higher in the study group in the week following the PRF injection compared to the other weeks (P < .05), there were no significant differences in the control group at all-time points (P > .05). Applying i-PRF significantly increased the rate of maxillary incisor retraction at all time intervals. Platelet-rich fibrin injection can be an effective method for shortening treatment duration.

Evaluation of root resorption after orthodontic treatment: A clinical study of contributory factors

Introduction: The aim of this study was to evaluate the contributory factors of external apical root resorption. Materials and Methods: Sixty subjects who had undergone complete orthodontic treatment were selected. The difference of the root length between pre and post-treatment was measured. The degree of root resorption was scored according to the index proposed by Levander and Malmgren. 1 The mean root resorption score (MRRS) was calculated. Mann Whitney test was done to compare the groups. Pearson correlation was applied. Results: There was no statistically significant difference in root resorption among males and females. Tooth extraction was correlated with MRRS. Except for upper posterior teeth, the duration of treatment was positively correlated with MRRS. For overjet, there was a positive correlation between upper and lower anterior teeth and MRRS. Conclusion: Orthodontic treatment should be carefully performed in patients who need extraction, great retraction of maxillary incisors and prolonged therapy. Keywords: Root resorption, Fixed orthodontic treatment forces.

Alveolar bone response to maxillary incisor retraction using stable skeletal structures as a reference.

To evaluate alveolar bone change in relation to root position change after maxillary incisor retraction via cone-beam computed tomography (CBCT) using stable skeletal structures as a reference. A total of 17 subjects (age 24.7 ± 4.4 years) who required retraction of the maxillary incisors were included. Labial and palatal alveolar bone changes and root change were assessed from preretraction and 3 months postretraction CBCT images. The reference planes were based on stable skeletal structures. The Kruskal-Wallis test and Wilcoxon signed-rank test were used to compare changes within and between groups, as appropriate. Spearman rank correlations were used to identify the parameters that correlated with alveolar bone change. The significance level was set at .05. The labial alveolar bone change after maxillary incisor retraction was statistically significant (P < .05), and the bone remodeling/tooth movement (B/T) ratio was 1:1. However, the palatal bone remained unchanged (P > .05). The change in inclination was significantly related to labial alveolar bone change. Using stable skeletal structures as a reference, the change in labial alveolar bone followed tooth movement in an almost 1:1 B/T ratio. Palatal alveolar bone did not remodel following maxillary incisor retraction. The change in inclination was associated with alveolar bone change.

A study on the morphologic change of palatal alveolar bone shape after intrusion and retraction of maxillary incisors

The purpose of this study is to evaluate the changes in the palatal alveolar bone thickness and find the factors related to the resorption of the palatal alveolar bone caused by tooth movement after the maxillary incisors were retracted and intruded during orthodontic treatment. The study group comprised of 33 skeletal Class II malocclusion patients who underwent extraction for orthodontic treatment. Palatal alveolar bone thickness changes and resorption factors were identified and analyzed. The changes of maxillary central incisors and palatal alveolar bone thickness were measured, and the corresponding sample t test was performed using SPSS (IBM SPSS version 22). The amount of palatal alveolar bone resorption was measured and various parameters were analyzed to determine which factors affected it. Correlation analysis adopting the amount of palatal alveolar bone resorption as a dependent variable demonstrated that the SNB, mandibular plane angle, and the inclination of the maxillary central incisor were significantly correlated with before treatment. On the other hand, mandibular plane angle, angle of convexity, the inclination of the upper incisor, and the occlusal plane (UOP, POP) were significantly correlated with post-treatment. In addition, the variables related to palatal contour (PP to PAS, SN to PAS, palatal surface angle) and occlusal planes (UOP/POP) were significantly correlated with the difference in palatal bone resorption. During initial diagnosis, high angle class II with normal upper incisor inclination can be signs of high-risk factors. In addition, maintaining the occlusal plane during treatment helps to prevent palatal bone loss.

Evaluation of open bite closure using clear aligners: a retrospective study

ObjectivesTo evaluate the dental and skeletal effects that occur in the correction of anterior open bite with clear aligners.Materials and methodIn this single-center retrospective study, the mechanism of anterior open bite closure using clear aligners (Invisalign, Align Technology, Santa Clara, CA, USA) was evaluated by cephalometric superimposition based on records of patients consecutively treated by a single, experienced Invisalign provider. Inclusion criteria consisted of anterior open bite (overbite < 0.5 mm), adult patients (18+) at the beginning of treatment, consecutive records, and good quality pre- and post-treatment records, where the required landmarks were clearly visible.ResultsA total of 45 patients were included for data analysis with a mean age of 30.73 ± 8.0 years and initial open bite of − 1.21 ± 1.15 mm. During treatment, the upper incisors showed significant (p < 0.05) retraction [U1-SN′(°) = − 10.91 ± 6.95°], [U1-SN′perp(mm) = − 2.57 ± 1.75 mm] and extrusion [U1-SN′(mm) = 1.45 ± 0.89 mm]. The lower incisors also showed significant retraction [IMPA(°) = − 3.73 ± 4.91°), (ΔL1-MP′perp (mm) = − 1.08 ± 1.59] and extrusion (ΔL1-MP′(mm) = 0.53 ± 0.74). Regarding molar position, no significant changes were noted in the anteroposterior position of the upper [ΔU6-SN′perp(mm) = 0.01 ± 1.08 mm] and lower molar [ΔL6-MP′perp(mm) = 0.03 ± 0.87 mm]; however, there was a statistically significant intrusion of the upper [ΔU6-SN′(mm) = − 0.47 ± 0.59 mm] and lower molar [ΔL6-MP′(mm) = − 0.39 ± 0.76 mm].ConclusionOpen bite closure with clear aligners occurred due to a combination of maxillary and mandibular incisor extrusion and maxillary and mandibular molar intrusion, with slight mandibular auto rotation. Significant retraction of maxillary and mandibular incisors was also observed with treatment. Clear aligners are effective in reducing/controlling the vertical dimension in open bite patients.

Clear aligners for maxillary anterior en masse retraction: a 3D finite element study

To evaluate tooth behaviours under various maxillary incisor retraction protocols for clear aligner therapy. A three-dimensional finite element model of maxillary dentition was constructed for first premolar extraction. A loading method was developed to mimic the mode of action of clear aligners for incisor en masse retraction. Three protocols with different amounts of retraction and intrusion on incisors were designed. Initial tooth displacements and stresses on periodontal ligaments were analysed with ANSYS software. The central (U1) and lateral (U2) incisors exhibited uncontrolled lingual tipping and extrusion upon 0.25 mm retraction. U1 exhibited translation movement, while U2 underwent less tipping during 0.2 mm retraction and 0.15 mm intrusion. Labial tipping and intrusion of U1 and bodily intrusion of U2 were observed during 0.1 mm of retraction and 0.23 mm of intrusion. With the additional intrusion on incisors, canine showed extrusion movement, and higher stresses on periodontal ligaments were shifted from U2 to canines. Incisors also exhibited different mesial-distal angulation in the three simulations, while posterior teeth all suffered mesial inclination. Incorporating intrusion displacement in clear aligners led to a tendency of lingual root movement during incisor retraction. The complexity of tooth movement should be recognized regarding clear aligner therapy.

Evaluation of growth changes induced by functional appliances in children with Class II malocclusion: Superimposition of lateral cephalograms on stable structures.

ObjectiveTo compare short- and long-term dentoalveolar, skeletal, and rotational changes evaluated by Björk’s structural method of superimposition between children with Class II malocclusion treated by functional appliances and untreated matched controls.MethodsSeventy-nine prepubertal or pubertal children (mean age, 11.57 ± 1.40 years) with Class II malocclusion were included. Thirty-four children were treated using an activator with a high-pull headgear (Z-activator), while 28 were treated using an activator without a headgear (E-activator). Seventeen untreated children were included as controls. Lateral cephalograms were obtained before treatment (T1), after functional appliance treatment (T2), and after retention in the postpubertal phase (T3). Changes from T1 to T2 and T1 to T3 were compared between the treated groups and control group using multiple linear regression analysis.ResultsRelative to the findings in the control group at T2, the sagittal jaw relationship (subspinale-nasion-pogonion, p < 0.001), maxillary prognathism (sella-nasion-subspinale, p < 0.05), and condylar growth (p < 0.001) exhibited significant improvements in the Z- and E-activator groups, which also showed a significantly increased maxillary incisor retraction (p < 0.001) and decreased overjet (p < 0.001). Only the E-activator group exhibited significant backward rotation of the maxilla at T2 (p < 0.01). The improvements in the sagittal jaw relationship (p < 0.01) and dental relationship (p < 0.001) remained significant at T3. Condylar growth and jaw rotations were not significant at T3.ConclusionsFunctional appliance treatment in children with Class II malocclusion can significantly improve the sagittal jaw relationship and dental relationships in the long term.

Cone beam computed tomographic-Based retrospective study on newark population for the assessment of distance between incisive canal and maxillary central incisors: Clinical implications.

To calculate the relative distance between the incisive canal and maxillary central incisors using cone beam computed tomography (CBCT) and utilize the results in treatment planning in a clinical setting. A retrospective study was conducted on CBCT taken for other purposes in the Oral and Maxillofacial Radiology Department. All the quantitative measurements were performed between the incisive canal and both maxillary central incisors using CBCT on 61 subjects. The anterior-posterior measurements were taken on both sides and the average of both values was considered for the statistical analysis. All the linear measurements were performed on the axial plane at three different vertical reference points located on the sagittal plane. The interexaminer reliability was tested by interclass correlation coefficient using two-way mixed and absolute agreement model. The comparison of linear measurement among each level was done by "Repeated measure ANOVA" and contrast method was used for pair-wise comparison when repeated measure analysis of variance (ANOVA) was significant. The average anterior-posterior distance between the maxillary central incisor roots and the incisive canal measured was approximately 5-6 mm. The incisive canal width increases from the root apex level of maxillary central incisors (P3) to the oral opening level of the incisive canal (P1). The results of our study could be helpful in a clinical setting requires significant retraction of maxillary incisors or implant placement in maxillary anterior region.

Alveolar bone remodeling during maxillary incisor intrusion and retraction

BackgroundMaxillary incisor protrusion is a prevalent dental deformity and is often treated by upper incisor intrusion and retraction. The mechanical loading triggers the resorption and apposition of the bone. Alveolar bone remodeling is expected to follow orthodontic tooth movement in a one-to-one relationship. However, in many cases, the outcomes are different. Alveolar bone might still remain thick causing lip protrusion and other aesthetic problems after treatment. Additional corrective procedures such as alveoloplasty. On the other hand, if the labial bone becomes too thin, periodontal problems like gingival recession might occur. The unpredictability of the treatment result and the risk of requiring corrective procedures pose significant challenges to both the providers and patients. The aim of this study is to determine factors that can help to predict the alveolar bone reaction before maxillary incisor intrusion and retraction.MethodsThe cohort included 34 female patients (mean age 25.8 years) who were diagnosed with skeletal class II malocclusion with upper incisor protrusion. These patients underwent extraction and orthodontic treatment with upper incisor intrusion and retraction. Lateral cephalograms at pre-treatment and post-treatment were taken. Linear and angular measurements were analyzed to evaluate the alveolar bone changes based on initial conditions.ResultsThe study found that the relative change, calculated as change in alveolar bone thickness after treatment divided by the initial alveolar thickness, was inversely correlated with the initial thickness. There was a significant increase of labial alveolar bone thickness at 9-mm apical from cementoenamel junction (B3) (P < 0.05) but no statistically significant change in the thickness at other levels. In addition, the change in angulation between the incisor and alveolar bone was inversely correlated with several initial angulations: between the initial palatal plane and upper incisor angle, between the initial palatal plane and upper incisor labial surface angle, and between the initial palatal plane and bone labial surface angle. On the other hand, the change in labial bone thickness was neither significantly correlated with the initial thickness nor significantly correlated to the amount of retraction.ConclusionThe unpredictability of alveolar bone remodeling after upper incisor intrusion and retraction poses significant challenges to treatment planning and patient experience. The study showed that the initial angulation between the incisor and alveolar bone is correlated with the change in angulation after treatment, the initial thickness of the alveolar bone was correlated with the relative change of the alveolar bone thickness (defined as change in thickness after treatment divided by its initial thickness), and the amount of intrusion was correlated with the alveolar bone thickness change at 9-mm apical from the cementoenamel junction after treatment. The results of the present study also revealed that the change in labial alveolar bone thickness was neither significantly correlated with the initial thickness nor significantly correlated to the amount of retraction.

Establishment of three-dimensional measurement methods of nasolabial soft tissue for patients with maxillary protrusion

OBJECTIVE To establish a series of three-dimensional measurement methods of nasolabial soft tissue for maxillary protrusion patients by using 3dMD camera, and to evaluate preoperative and postoperative changes of the nasolabial soft tissue. METHODS Three-dimensional facial photos of 30 female patients with maxillary protrusion [average age, (27.33±2.54) years] were taken by 3dMD camera preoperatively and at the end of postoperative 6 months or more. Then, 3dMD patient software was used to locate the selected landmarks at nasolabial region on the three-dimensional photos. Ten measurements, including soft tissue line distance, angle, curve distance and postoperative three-dimensional volume changes were measured twice with one week interval by 3 investigators, respectively. A standard consistency test calculated by the correlation coefficients (ICC) was performed between two sets of data (including all of the 10 measurements) for each investigator and among the three investigators to verify the repeatability. RESULTS The average maxillary incisor retraction distance of the 30 subjects was (5.13±0.99) mm, and the average follow-up time was (11.07±5.11) months. The standard consistency test was performed between the two sets of data for each investigator, and the correlation coefficients (ICC) of the 10 measurements were all over 0.8 for each investigator (P>0.05). The standard consistency test was performed among the three surveyors, with the result that the ICC of the width of the bilateral inner canthus, the height of the nose, the height of nasal tip, nasolabial angle, philtrum length, the curve height of upper vermilion and the height of upper lip were greater than 0.8 (P>0.05), and the ICC of the distance between SbalSbal, length of nasal dorsum and three-dimensional volume change of upper lip were 0.680, 0.627 and 0.528, respectively (P>0.05). CONCLUSION 3dMD camera and 3dMD patient software can be used to measure and analyze the three-dimensional morphology of the nasolabial soft tissue for patients with maxillary protrusion preoperatively and postoperatively, and it is relatively accurate and reliable. However, the repeatability of three-dimensional positioning of the nasal tip point and the Sbal is slightly worse resulting in the lower value of the ICC of the distance between SbalSbal and length of nasal dorsum, as well as the upper lip three-dimensional volume change after the operation.

CONE BEAM COMPUTED TOMOGRAPHIC ASSESSMENT OF THE DISTANCE BETWEEN THE INCISIVE CANAL AND MAXILLARY CENTRAL INCISORS

Background Maxillary anterior teeth play an important role in aesthetics, phonetics, and mastication. Because of the aesthetic and functional significance, it is important to evaluate their position in association with surrounding structures in 3-D before initiating orthodontic treatment. With the advent of cone beam computed tomography (CBCT) in orthodontic diagnosis, it is now possible to identify these structures. One such structure is the incisive canal. Uncertainty in locating the canal can cause root resorption postorthodontic retraction of anterior maxillary teeth. Objective(s) The aim of this study was to calculate the relative distance between the incisive canal and maxillary central incisor using CBCT and utilize the results for orthodontic treatment planning. Study Design All quantitative measurements between the incisive canal and both maxillary central incisors were performed using CBCT on 61 patients. The anteroposterior measurements were taken on both sides, and the average of both values was considered for the statistical analysis. The Steiner cephalometric analysis was performed to select patients with skeletal and dental Class I relationship. All linear measurements were performed on the axial plane at 3 different vertical reference points located on the sagittal plane: (1) the palatal opening of the incisive canal (opening level, P1), (2) midlevel between the opening level and the root apex of the maxillary central incisors (midlevel, P2), and (3) the root apex of the maxillary central incisors (root apex level, P3). Results The average anteroposterior distance between the maxillary central incisor roots and the incisive canal was approximately 56 mm. Discussion/Conclusions The results of our study could be clinically helpful to plan orthodontic treatment that requires significant retraction of maxillary incisors. The authors support the idea of a pretreatment CBCT in cases that require maximum anterior retraction in the maxilla. Maxillary anterior teeth play an important role in aesthetics, phonetics, and mastication. Because of the aesthetic and functional significance, it is important to evaluate their position in association with surrounding structures in 3-D before initiating orthodontic treatment. With the advent of cone beam computed tomography (CBCT) in orthodontic diagnosis, it is now possible to identify these structures. One such structure is the incisive canal. Uncertainty in locating the canal can cause root resorption postorthodontic retraction of anterior maxillary teeth. The aim of this study was to calculate the relative distance between the incisive canal and maxillary central incisor using CBCT and utilize the results for orthodontic treatment planning. All quantitative measurements between the incisive canal and both maxillary central incisors were performed using CBCT on 61 patients. The anteroposterior measurements were taken on both sides, and the average of both values was considered for the statistical analysis. The Steiner cephalometric analysis was performed to select patients with skeletal and dental Class I relationship. All linear measurements were performed on the axial plane at 3 different vertical reference points located on the sagittal plane: (1) the palatal opening of the incisive canal (opening level, P1), (2) midlevel between the opening level and the root apex of the maxillary central incisors (midlevel, P2), and (3) the root apex of the maxillary central incisors (root apex level, P3). The average anteroposterior distance between the maxillary central incisor roots and the incisive canal was approximately 56 mm. The results of our study could be clinically helpful to plan orthodontic treatment that requires significant retraction of maxillary incisors. The authors support the idea of a pretreatment CBCT in cases that require maximum anterior retraction in the maxilla.

Force direction using miniscrews in sliding mechanics differentially affected maxillary central incisor retraction: Finite element simulation and typodont model

Background/purposeEn masse retraction was still controversy in orthodontics. The aim of this study was to investigate the effect of force directions created by different miniscrew positions and lever arm heights on maxillary central incisor movement using Finite Element (FE) simulation and a Typodont model. Materials and methodsA typodont model and 3-dimensional FE were used to simulate en masse anterior teeth retraction in sliding mechanics. The lever arm and the miniscrew positions were varied to change the force direction. The maxillary central incisor displacement was recorded and analyzed. ResultsThe typodont results revealed that miniscrew vertical position and lever arm height affected the type of tooth movement. The best control in the vertical plane was achieved by a 7 mm lever arm height and miniscrew 9 mm from the archwire. When the lever arm height and miniscrew were 7 mm from the archwire, the tooth extruded. When the lever arm height was 9 mm and the miniscrew was 7 or 9 mm from the archwire, the tooth intruded. The FE stimulation determined that near bodily movement of the maxillary central incisor was achieved when the lever arm height and miniscrew was 9 mm from the archwire. The highest strain distribution in the periodontal ligament was observed at the apical third of the lateral incisor. ConclusionIn en masse retraction, the appropriate direction of force or the height of the miniscrew and the lever arm may enable orthodontists to maintain better control of the anterior teeth in sliding mechanics.

Apical root resorption in patients treated with en-masse retraction using skeletal anchorage system versus conventional method

Purpose: To compare external apical root resorption EARR in orthodontic patients treated with en-masse retraction with skeletal anchorage (miniscrews) versus two step procedures. Patients and methods: Forty patients were randomly divided into two equal groups. Group I consisted of 20 patients were treated by using mini-screw anchorage and en-masse retraction, while, group II, 20 patients were treated with two-step retraction and conventional methods of anchorage reinforcement. Lateral cephalometric and digital panoramic radiographs were used to evaluate treatment changes just before (T1) and immediately after (T2) retraction of the maxillary anterior teeth. Results: A significant positive correlation between age and root resorption. Shorter treatment duration was needed in group I with insignificant difference between both groups. Significant root resorption in maxillary central, lateral incisors, canines and first molars was found in both groups just after retraction. A significant root resorption was found for maxillary centrals and first molars in mini-implant group compared to conventional anchorage group. Upper first molars were intruded (-1.8 mm, P=0.041) in mini-implant group with no significant distalization (P=0.016) compared to conventional anchorage group. Upper incisors were significantly retracted (-7.8mm, P=0.001) and intruded (-2.3mm, P=0.017) in comparison to other group. Conclusion: Skeletal anchorage system tends to permit more root resorption than conventional anchorage procedure. A significant retraction and intrusion of maxillary incisors, and a significant intrusion and lack of distalization of maxillary first molars by using skeletal anchorage system during en-masse retraction was found when compared with conventional anchorage procedure.

The role of lip thickness in upper lip response to sagittal change of incisor position.

To investigate the association between upper lip thickness and the amount of upper lip repositioning upon retraction of maxillary incisors. Pre- and post-treatment lateral cephalograms of 101patients were reviewed. All subjects were treated with fixed orthodontic appliances including extraction of two maxillary premolars. Only subjects without change in lip thickness between pre- and post-treatment cephalograms were included. Digital software measurements for lip thickness, pre- and post-treatment upper lip position were performed. Appropriate regression models were developed to explore the correlation between maxillary incisor retraction and lip retraction when controlling for lip thickness and other confounding factors. The level of statistical significance was set at 0.05 for all analyses. A significant correlation was found between change in maxillary incisor position following premolars extraction and change in upper lip position (r=0.95, P<0.001). The average ratio between maxillary incisor retraction and upper lip repositioning was 1.43:1. Upper lip thickness was not significantly associated with this ratio (r=0.003, P>0.05). Although there is a highly significant correlation between maxillary incisor retraction and upper lip repositioning, lip thickness is not significantly associated with the amount of repositioning.

Comparison of treatment effects between four premolar extraction and total arch distalization using the modified C-palatal plate.

ObjectiveThe purpose of this study was to compare the skeletal, dental, and soft-tissue treatment effects of nonextraction therapy using the modified C-palatal plate (MCPP) to those of premolar extraction (PE) treatment in adult patients with Class II malocclusion.MethodsPretreatment and posttreatment lateral cephalographs of 40 adult patients with Class II malocclusion were retrospectively analyzed. The MCPP group comprised 20 patients treated with total arch distalization of the maxillary arch while the PE group comprised 20 patients treated with four PE. Fifty-eight linear and angular measurements were analyzed to assess the changes before and after treatment. Descriptive statistics, paired t-test, and multivariate analysis of variance were performed to evaluate the treatment effects within and between the two groups.ResultsThe MCPP group presented 3.4 mm of retraction, 1.0 mm of extrusion, and 7.3° lingual inclination of the maxillary central incisor. In comparison, the PE group displayed greater amount of maxillary central incisor retraction and retroclination, mandibular incisor retraction, and upper lip retraction (5.3 mm, 14.8°, 5.1 mm, and 2.0 mm, respectively; p < 0.001 for all). In addition, the MCPP group showed 4.0 mm of distalization and 1.3 mm of intrusion with 2.9° distal tipping of the maxillary first molars.ConclusionsThese findings suggest the MCPP is an effective distalization appliance in the maxillary arch. The amount of incisor retraction, however, was significantly higher in the PE group. Therefore, four PE may be recommended when greater improvement of incisor position and soft-tissue profile is required.

Skeletal Anchorage for the Correction of Bimaxillary Protrusion and Gummy Smile

Many methods of achieving maximum anchorage have been experimented by various clinicians through the years. Usage of mini implants has its own limitations, inconsistent results being the most common. However, anchorage using mini plates produced consistent results even though it requires a minor invasive surgical procedure. The aim was to retract and correct a gummy smile of 5 mm, diagnosed to be due to a vertical maxillary excess, with mini plates used bilaterally in the zygomatic buttress region. A modified “L” shaped surgical stainless steel mini plate was inserted and stabilized with 3 screws in the anterior region of the zygomatic buttress and sutured with the tip of the surgical plate exposed in the oral cavity for the attachment of an elastomeric chain to the arch wire. The gummy smile was fully corrected with minimal intrusion of maxillary anteriors. Cephalometrically, there was intrusion and retraction of maxillary incisors with absolutely no anchor loss. The modified surgical mini plate is an excellent tool for the successful correction of the gummy smile and also has proved to be a very efficient absolute anchorage system for en masse retraction.

Three-dimensional assessment of condylar position and joint spaces after maxillary first premolar extraction in skeletal Class II malocclusion.

This study sought to investigate the three-dimensional (3D) changes in anteroposterior, vertical and mediolateral positions and orientations of the mandibular condyle as well as joint space parameters following maxillary first premolar extraction and incisor retraction in skeletal Class II patients. Thirty patients were treated by orthodontic maxillary first premolar extraction at the Faculty of Oral and Dental Medicine, Cairo University, Egypt. Cone beam computed tomography (CBCT) analysis was performed in patients pre- and post-treatment. Sixty joints were evaluated based on the volumetric images, and the following 3D measurements were evaluated: (i) mandibular condylar position relative to the cranial base and the joint itself, (ii) condylar inclination and (iii) anterior, posterior, superior and medial joint spaces. There was a statistically significant (P≤.05) posterior positioning of the condyle relative to the vertical plane. The distance increased significantly from 5.77 to 6.82mm as this plane is anterior to the mandibular condyle. There was an increased anterior joint space (from 3.10 to 3.90mm) and decreased posterior joint space (from 2.78 to 2.23mm) following treatment. No changes were observed in mediolateral and vertical condylar positions. Posterior positioning of the condyle after orthodontic extraction and incisor retraction may occur, but its clinical significance requires further assessment in future studies.

Lip response to incisor movement in operated cleft lip and palate patients.

Although the literature has shown that the lip response to maxillary incisor retraction varies, these studies have been done on a noncleft lip/palate sample. The aim of this study is to evaluate response of operated cleft lip to orthodontic tooth movement and to determine if there are any differences in the response between the operated cleft lip and the noncleft lip. This was a hospital-based retrospective study using radiographs. Lip changes were evaluated using pre- and post-operative lateral cephalometric radiographs. The experimental group consisted of 12 patients with operated cleft lip while the control group consisted of 12 noncleft patients with dental and skeletal Class I malocclusion. ANOVA was used for statistical analysis. The operated lip responded less to incisor movement than the noncleft group (P < 0.05). While the cleft group demonstrated an increase in upper lip thickness measurements at Point A and vermilion following incisor retraction, the control group showed a decrease in thickness of the upper lip at Point A and an increase at vermilion. The cleft team should be aware that the operated lip responds differently to incisor movement. This will enable them to better plan comprehensive treatment for the cleft lip and palate patient.

Comparison of Apical Root Resorption encountered during Maxillary Incisor retraction using Stainless Steel Boot Loop and TMA Boot Loop – A Case Series

External apical root resorption (EARR) is probably the most common iatrogenic sequel of orthodontic treatment. The present case series focuses on the incisor retraction using frictionless mechanics. Boot loop made up of .019x.025 Stainless steel or TMA archwire were used for maxillary incisor retraction. Retraction with stainless steel boot loop showed greater root resorption as compared to TMA boot loop.Orthodontic Journal of Nepal, Vol. 6 No. 1, June 2016, pp.45-48