Bimaxillary Dentoalveolar Protrusion Research Articles

Effect of low-level laser therapy on en masse retraction in females with bimaxillary dentoalveolar protrusion : A single-center randomized clinical trial.

Acceleration of tooth movement has gained remarkable attention during the last decade. The aim of this study was to evaluate the effect of low-level laser therapy (LLLT) on en masse retraction of upper anterior teeth in adult women with bimaxillary dentoalveolar protrusion. In this two-arm parallel trial, 36women with bimaxillary dentoalveolar protrusion were randomly divided into two equal groups. Eligibility criteria included classI Angle molar relationship, good general and oral health as well as no systemic disease or syndrome. Four temporary anchorage devices (TADs) were used in the upper and lower arches for anchorage purposes. A 0.019×0.025-inch stainless steel wire with crimped hooks just distal to the maxillary canines was inserted. Nickle titanium (NiTi) closed coil springs (200 g/side) were employed for en masse retraction following extraction of the first premolars. In the laser group (LG), retraction of the upper anterior teeth was done along with the application of LLLT on days0, 3, 7, and 14 after extraction and then repeated biweekly until the end of retraction. Retraction was completed without LLLT application in the nonlaser group (NLG). Data concerning the rate of retraction as well as first molars and anterior positional changes were gained from digitized models and cone beam computed tomography (CBCT) scans taken just before extraction and at the end of retraction. Treatment-associated pain and root resorption were evaluated using visual analogue scale (VAS) and CBCT scans, respectively. Four patients dropped out prior to follow-up. The duration of retraction was 10.125 ± 2.876 and 13.643 ± 3.455 months in the LG and NLG, respectively. The LG showed astatistically significant faster rate of en masse retraction (0.833 ± 0.371 mm/month) compared to the NLG (0.526 ± 0.268 mm/month; P ≤ 0.035). The observed root resorption was significantly less in the LG (P ≤ 0.05) with comparable pain scores in both groups. Within the constraints of the parameters of the LLLT used in the current study and despite the statistically significant results on the rate of en masse retraction and the associated root resorption, LLLT did not demonstrate aclinically relevant effect that justifies its use to enhance en masse retraction. Clinicaltrials.gov TRIAL REGISTRATION NUMBER: NCT05183451 DATE OF REGISTRATION: January10, 2022, "Retrospectively registered" URL OF TRIAL REGISTRY RECORD: https://www. gov/study/NCT05183451.

Evaluation of anchorage loss after en masse retraction in orthodontic patients with maxillary protrusion using friction vs frictionless mechanics: randomized clinical trial

ABSTRACT Objectives To evaluate anchorage loss after en masse retraction in bimaxillary dentoalveolar protrusion patients using friction vs frictionless mechanics. Materials and Methods Thirty patients with bimaxillary dentoalveolar protrusion needing extraction of upper first premolars and en masse retraction with maximum anchorage were included in this two-arm, parallel, single-center, single-blinded randomized clinical trial with a 1:1 allocation ratio using fully sealed opaque envelopes. Friction group retraction utilized elastomeric power chain between miniscrews and hooks crimped mesial to upper canines on 17 × 25 stainless steel archwire. Frictionless group used customized T-loop springs loading upper first molars indirectly anchored to miniscrews. Activation was every 4 weeks until full retraction. The primary outcome assessed was anchorage loss evaluated at cusp tip and root apex of the first molar. First molar rotation, incisor tip and torque, and root resorption of anterior teeth were evaluated on digital models and cone beam computed tomography taken before and after space closure. Results Anchorage loss at crown of first molar was significantly more in frictionless group by 2.1 mm (95% CI = −0.4 to 3.5), (P = .014), while there was no significant difference in anchorage loss at root apex between groups. Significant mesial in molar rotation of 6.672° (95% CI = 12.2–21.2), (P = 0.02) was greater in the frictionless group. Both groups showed comparable tip, torque, and root resorption values. No severe harms were reported. There was mild gingival overgrowth and inflammation in the frictionless group due to T-loop irritation. Conclusions Extra anchorage considerations are needed during en masse retraction when frictionless mechanics is implemented as higher anchorage loss and molar rotation were detected. No difference in tip, torque, and root resorption was observed.

Efficiency of friction versus frictionless mechanics for correcting bimaxillary dentoalveolar protrusion in dizygotic twins – A case report

The purpose of this case presentation is to determine the efficiency of two treatment mechanics in correcting clinically comparable malocclusion in dizygotic twins. The case report describes the orthodontic management of 19-year-old non-identical twins diagnosed with bimaxillary dentoalveolar protrusion on a Class I skeletal base with severe crowding using two different treatment mechanics. The first patient was treated with frictionless mechanics by making use of Kalra simultaneous intrusion and retraction arch for space closure, whereas the friction mechanics accomplished the task in the second patient with mini-implant (Titanium mini-implant, FavAnchor™ SAS, Favorite supplies, Thane west, Maharashtra, India) assisted power arm (Power hook, Azdent Orthodontics, Zhengzhou, China) retraction. It evaluated the overall treatment duration, anterior torque control, and level of comfort for the patients with the two mechanics. The post-treatment results in both cases exhibited remarkable change in inclination of upper anterior teeth which were established through cephalometric findings. Moreover, the anterior torque control was comparatively superior with loop mechanics over mini-implant assisted sliding mechanics. Both the treatment mechanics effectively and efficiently corrected the malocclusion with considerable impact on soft-tissue profile.

Bimaxillary dentoalveolar protrusion associates with labially angulated mandibular canine and mesial inclined mandibular first premolars—Based on CBCT image measurements

BackgroundBimaxillary dentoalveolar protrusion is a frequent complain in orthodontic clinic. The incisor angulation and inclination have been largely discussed. The present purpose was to assess the involvement of the teeth distal to incisors. MethodsIn this cross-sectional study, 63 patients with Class I occlusion and an average sagittal relationship between the maxilla and mandible were enrolled. Twenty-two cases (20.14 ± 7.32 years old) who had protrusion profile and flaring upper and lower incisors were diagnosed as bimaxillary dentoalveolar protrusion. The other 41 cases (21.87 ± 7.15 years old) who had a balanced facial profile and mild anterior crowding were taken as controls. The buccolingual angulation and the mesiodistal inclination of the canines and premolars, which had single root, revealed on the cone-beam computed tomography (CBCT) images were measured. The values of the angulation and inclination were compared between the two groups by using Student t-test methods (α = 0.05). ResultsThe bilateral mandibular canines were more labially angulated (P＜0.001) but the bilateral mandibular first premolars were more mesial inclined in the bimaxillary dentoalveolar protrusion group than that in the control group (for tooth 34,P < 0.002; for tooth 44, P < 0.010). ConclusionsMore labial angulated mandibular canine and more mesial inclined mandibular first premolars associate with bimaxillary dentoalveolar protrusion. The labial-lingual angulation of the mandibular canines and the mesial-distal inclination of the mandibular first premolar should be paid a specially attention during the development, thus, the early intervention of the bimaxillary dentoalveolar protrusion.

Effect of First Premolars Extraction with Maximum Retraction on Airway and Hyoid Bone Position in Class I Bimaxillary Dentoalveolar Protrusion Cases

Background: The aim was to determine the effect of first premolars extraction with maximum incisor retraction on airway magnitude and hyoid bone position in cases with bimaxillary dentoalveolar protrusion. Methods: Lateral cephalograms of patients with Class I skeletal and dental relationships were retrospectively recruited. Inclusion criteria were 15-30 years old patients having bimaxillary proclination who had undergone all first premolar extractions with maximum incisor retraction. Patients with dentofacial anomalies, chronic mouth breathing and those who had undergone tonsillectomy or adenoidectomy were excluded. Pre-and post-treatment lateral cephalograms were digitally analyzed for airway measurements and hyoid bone position. Paired samples T-test was used for statistical analysis. P-value&lt;0.05 was considered statistically significant. Results: A total of 33 patients, comprising 22 females and 11 males, with a mean age of 24.39 ± 6.92 years were included. Statistically significant differences were found in airway dimensions from pre-treatment to post-treatment; upper airway size between soft palate and posterior pharyngeal wall (SPP-SPPW) was reduced by 1.91mm (12.78%), at uvula &amp; middle posterior wall (U-MPW) by 2.51mm (20.60%), at tongue base to posterior-inferior point on middle pharyngeal wall (TB-TPPW) by 3.39mm (24.26%) and vallecular to lower pharyngeal wall by 1.51mm (9.94%). The vertical position of hyoid bone also significantly reduced as indicated by inferior movement of hyoidale (H) by 4mm (3.8%). There was no significant changes in the horizontal position of the hyoid bone. Conclusion: Premolar extraction with maximum retraction in bimaxillary protrusion cases can decrease the airway dimension and increase vertical position of hyoid bone.

Orthodontic treatment of traumatically avulsed maxillary central incisors with bimaxillary dentoalveolar protrusion in an adult female: a case report

BackgroundClinicians agree that obtaining and retaining good treatment results for missing maxillary central incisors owing to trauma is not easy. Management of adult patients with permanent maxillary central incisor loss who visit the clinic with high expectations for aesthetics and function pose a significant diagnostic dilemma. Therefore, esthetic and functional outcomes should be taken into consideration when deciding the proper treatment method. The treatment described in this study aimed to reestablish smile esthetics by proposing an effective multidisciplinary clinical approach that includes orthodontic-prosthetic-periodontal procedures, optimally reduced lip protrusion, center dental midlines, and establishment of stable occlusion.Case presentationThe patient was a 19-year-old adult female with bimaxillary arch protrusion who had been wearing removable dentures for several years since the loss of her maxillary central permanent incisors. A multidisciplinary treatment including the extraction of two mandibular primary premolars was adopted. The treatment plan consisted of orthodontic space closure by shifting the adjacent teeth towards the central incisor spaces combined with appropriate morphologic remodeling and gingival reshaping to obtain good aesthetic and functional results. The duration to complete the orthodontic treatment was 35 months. Clinical and radiographic results after treatment suggested smile harmony with an improvement in the facial profile, good function of the occlusion, and a positive effect on bone remodeling in the area of the missing incisors during orthodontic tooth movement.ConclusionsThis clinical case illustrated the necessity for using multidisciplinary methods involving orthodontic, prosthodontic, and periodontic procedures to treat an adult female patient with bimaxillary arch protrusion and long-term absence of anterior teeth due to severe trauma.

Changes in Third Molar Position after En-masse Retraction in Bimaxillary Dentoalveolar Protrusion Cases

Changes in Third Molar Position after En-masse Retraction in Bimaxillary Dentoalveolar Protrusion Cases

Long-term morphometric changes in the anterior alveolar bone in adolescents and adults after space closure: A retrospective study.

To analyse the morphometric changes in the anterior alveolar bone of both the maxilla and mandible after space closure and retention for 18-36 mo in adults and adolescents. Forty-two subjects with 4 first premolars extracted followed by retracting anterior teeth were included and divided into two age groups: adult group (4 males, 17 females, mean age: 23.67 ± 5.29 y, treatment duration: 27.95 mo, retention duration: 26.96 mo, ANB: 4.8 ± 2.1, U1-L1: 117.2 ± 9.2, U1-PP: 120.2 ± 7.2, L1-MP: 99.2 ± 5.3) and adolescent group (6 males, 15 females, mean age: 11.52 ± 1.21 y, treatment duration: 26.18 mo, retention duration: 25.79 mo, ANB: 5.2 ± 2.1, U1-L1: 116.0 ± 8.6, U1-PP: 119.8 ± 4.9, L1-MP: 99.7 ± 4.9). Alveolar bone height and thickness of anterior teeth in both groups were measured using cone beam computed tomography (CBCT) imaging performed at the pretreatment (T1), posttreatment (T2) and retention phases (T3). One-way repeated-measure ANOVAs were performed to evaluate the alveolar bone changes. Voxel-based superimpositions were performed to measure the amount of tooth movement. After orthodontic treatment, the lingual bone height and thickness of both arches and the labial bone height of the mandible decreased significantly in both age groups (P < .05). Most of the labial bone height and thickness of the maxilla in both groups remained unchanged (P > .05). After retention, the lingual bone height and thickness increased significantly in both age groups (P < .05). The amounts of increased height ranged from 1.08 to 1.64 mm in adults and from 0.78 to 1.21 mm in adolescents, and the amounts of increased thickness ranged from 0.23 mm to 0.62 mm in adults and from 0.16 mm to 0.36 mm in adolescents. Obvious movements of the anterior teeth during retention were not found (P > .05). Although lingual alveolar bone loss occurred in adolescents and adults during orthodontic treatment, continuous remodelling occurred in the later retention phase, which provides a reference for clinical treatment planning of bimaxillary dentoalveolar protrusion.

Treatment of an anterior open bite, bimaxillary protrusion and mesiocclusion by the extraction of premolars and the use of clear aligners

Abstract An anterior open bite may be orthodontically treated by either the intrusion of posterior teeth, the extrusion of anterior teeth, or a combination of both. An improvement in bimaxillary protrusion often involves the extraction of premolars and the retraction of the anterior teeth. The treatment of mesiocclusion mainly involves the mesial and/or distal movement of the molars. However, these three types of malocclusions pose significant treatment challenges when using clear aligners. The present case report describes the treatment of a 24-year-old female patient who presented with the above characteristics, which affected her confidence, willingness to smile and masticatory function. A four-premolar extraction plan was designed to resolve the problems using clear aligners as the patient rejected fixed or visible appliances. After 33 months of orthodontic therapy, except for the counter-clockwise rotation of the mandible and the decrease of facial height, the other objectives established in the pre-treatment plan were achieved, and the patient was satisfied with the results. The combination of clear aligners and premolar extractions effectively corrected the skeletal anterior open bite, bimaxillary dentoalveolar protrusion, and mesiocclusion.

Effect of a Submucosal Injection of Platelet-Rich Plasma on the Rate of Orthodontic Tooth Movement - A Split-Mouth, Single-Blind Randomized Controlled Trial.

To investigate the effect of submucosal injection of platelet-rich plasma (PRP) on the rate of mini-implant-supported retraction, using a split-mouth randomized clinical design. Twenty subjects of either gender between 16 and 25 years of age with bimaxillary dentoalveolar protrusion and crowding of <4 mm scheduled to undergo fixed mechanotherapy with the extraction of 1st premolars; were recruited for the study. Those with a periodontally compromised dentition, blood dyscrasias, smoking/alcoholism, or with a history of fixed orthodontic treatment were not considered. The intervention side received a submucosal injection of autologous PRP which was prepared using 10 ml of the patient's blood. The rate of extraction space closure on both sides was recorded and compared monthly for 3 months using a digital caliper. Mean overall retraction was faster on the intervention side as compared to the control side by 1.5 times and was statistically significant with a P value of 0.001. There was no influence of gender on the rate of retraction. There was no reported swelling or discomfort associated with the PRP injection. Submucosal injection of PRP significantly accelerates orthodontic tooth movement and can therefore be used as an effective, safe, and minimally invasive method to expedite orthodontic treatment.

Comparative Evaluation of Orthodontically-Induced Root Resorption Using Cone Beam Computed Tomography (CBCT) and Orthopantomogram (OPG) During En-Masse Retraction of Maxillary Anterior Teeth.

Orthodontically induced apical root resorption is an inescapable consequence of fixed orthodontics. This root resorption causes post-orthodontic complications in some treated cases. To avoid these complications proper diagnosis of the site and amount of resorption is important. The aim of this study was to compare the diagnostic ability of Orthopantomogram (OPG) and Cone Beam Computed Tomography (CBCT) in detecting apical root resorption after en-masse retraction of maxillary anterior teeth in a sample of Saudi Arabian population. The study sample comprised of 30 patients diagnosed with bimaxillary dentoalveolar protrusion. The treatment plan involved extraction of all first premolars followed by en-masse retraction of the anterior teeth. OPG images were obtained at the beginning of treatment and after the end of the retraction phase and a CBCT image were also obtained for the same patient at the same centre other than orthodontic reason like implant placement, temporomandibular joint (TMJ) problems, sleep apnea, etc. after orthodontic treatment completion. The scoring system of Levander and Malmgren was used to assess the degree and severity of root resorption in the maxillary incisors. Dalhbergs error and coefficient of reliability (ICC) were used to calculate the correlation between the two sets of readings.Pearson chi-square test was used to compare the difference in root resorption between OPG and CBCT images. A P-value of <0.05 was considered to be statistically significant. No resorption was observed in 39.2%and 16.6% of incisors with OPG and CBCT respectively. Mild resorption was observed in 50% and 66.7% of incisors with OPG and CBCT respectively. Moderate resorption was found in 10% and 15% of incisors with OPG and CBCT respectively. Severe root resorption was found in 0.8% and 1.7% of incisors with OPG and CBCT respectively. Statistically, significant differences were found in both methods of evaluation in all grades of root resorption for all the maxillary incisors (P<0.05). OPG had consistently underestimated the amount of orthodontically induced apical root resorption when compared to CBCT. OPG is only useful for the primary evaluation of root resorption. CBCT can be used as an adjunct diagnostic tool on a case-to-case basis in patients with moderate to severe root resorption to manage post-orthodontic treatment complications.

What are the surgical risks and 2-year stability of mandibular anterior subapical osteotomy in the treatment of dentoalveolar protrusion?

To investigate the stability and complications of mandibular anterior subapical osteotomy (ASO) in the treatment of bimaxillary dentoalveolar protrusion by way of a retrospective study. One hundred and twenty patients who received orthognathic surgery at a single center between 2008 and 2017 were included. Relapse was assessed by serial tracings of lateral cephalograms which were obtained pre-operatively (T1), within 6weeks after surgery (T2) and at 2years after surgery. The changes between T2 and T3 represented stability and were tested using the paired t test. The relationship between the extents of surgical repositioning (T2-T1) and relapse (T3-T2) was investigated using the Pearson correlation coefficient. The associations between the variables and the occurrence of relapse and complications identified the risk factors and were evaluated using the χ2 test or Fisher's exact test. When r > 0.80, clinical correlation was considered significant; and statistical significance was set at P < 0.05, while confidence interval was set at 95%. There was a mean uprighting of L1-MP by 12.7°. At 2years after surgery, 96.7% of the patients experienced a mean relapse of L1-MP by 2.9°. The extent of surgical repositioning was only weakly correlated with that of relapse and no specific factor that increased the risk of relapse could be identified. The most frequent complications were blood loss requiring transfusion, wound dehiscence or infection, gingival recession, and periodontal bone loss, involving 25.8 to 43.3% of the patients. The remaining complications included tooth root damage, fixation hardware exposure or infection, lingual mucosal laceration, and tooth devitalization. There were no cases of avascular necrosis or nonunion. Although relapse occurred in most of the patients after 2years, the actual extent was small (2.9°) which was not likely to be clinically significant. HKUCTR-2964 CLINICAL RELEVANCE: Although ASO may be valuable in correcting mandibular dentoalveolar protrusion, the procedure brings with it risks and complications and should be reserved for severe deformities.

Effects of autologous leukocyte-platelet rich fibrin (L-PRF) on the rate of maxillary canine retraction and various biomarkers in gingival crevicular fluid (GCF): A split mouth randomized controlled trial

Primary objective: To evaluate the effect of L-PRF on the rate of maxillary canine retraction. To validate the rate of maxillary canine retraction by identifying the levels of Interleukin-1β (IL-1β) and Tumour Necrosis Factor-α (TNF-α) in the Gingival Crevicular Fluid (GCF). Fifteen females (age range, 18-25 years) with Class I bimaxillary dentoalveolar protrusion malocclusions were included. After levelling and alignment of maxillary arches, 1st premolars were extracted from both sides. Canines were retracted immediately after the extraction of 1st premolars in control sides and placement of L-PRF plugs in the experimental sides. The amount of canine retraction was evaluated from study models recorded before the extraction of 1st premolars (T0) and at 1-week (T1), 2-weeks (T2), 4-weeks (T3), and 8-weeks (T4) after the beginning of canine retraction by using digital model superimpositions. The concentrations of IL-1β and TNF-α were evaluated from the GCF collected at T0, T1, T2, T3, and T4 by using commercially available human IL-1β and TNF-α ELISA kits. The amount of canine retraction in the experimental sides was statistically greater during T0-T1 (P=0.038),T1-T2 (P=0.002), and T2-T3 (P=0.011) periods. Total canine retraction during T0-T4 was statistically greater in experimental sides (2.43±0.46mm) than control sides (2.08±0.28mm) (P=0.001). The concentration of IL-1β increased significantly in the experimental sides at T1 (P=0.000),T2 (P=0.000), and T3 (P=0.032). The concentration of TNF-α increased both in the control and experimental sides, but it was statistically greater in the experimental sides compared to control sides at T1 (P=0.000) and T2 (P=0.006). A positive but not statistically significant correlation was noted between the rate of canine retraction and the concentrations of cytokines such as IL-1β and TNF-α in GCF. Over an 8-week period, autologous L-PRF statistically accelerated the rate of maxillary canine retraction, but only by 0.35mm. This small acceleration occurred mainly in the first 4 weeks. During the following 4 weeks, the amount of canine retraction was comparable on the experimental and control sides.

Palatal Anterior Teeth Retraction Assisted by Temporary Anchorage Devices - A Review

Successful orthodontic resolution of bimaxillary dentoalveolar protrusion depends on successful retraction of anterior dentition, which also involves acquiring proper buccolingual inclination and vertical position of anterior teeth. To fulfill these requirements, clinicians have devised numerous biomechanical and surgical orthodontic options. A palatal retractor for retraction of maxillary anterior dentition is the result of clinician’s long-time creative endeavors and an evolution of the biomechanical design. A palatal retractor splints the maxillary anterior dentition on the lingual side with bonded mesh plates connected by a supporting wire. Two long palatally extended arms are soldered to the supporting wire where adequate retraction force can be applied. Palatal retractors have several advantages over conventional bracket/wire systems. The two most prominent ones are biomechanical superiority and esthetic invisibility. As the palatal retractor is positioned on the lingual surface of the maxillary anterior dentition, it is not visible from the frontal view and since the anterior dentition retraction constitutes a significant portion of the total treatment time in extraction orthodontic treatment, it is a distinct esthetic advantage. Biomechanical disadvantage of the conventional bracket/wire system lies in its innate ineffectiveness of the torque and vertical control because of the long distance between the point of force application and the center of resistance of the anterior dentition. A combination of TADs and palatal retractors provides the possibility of maximizing control of both the torque and vertical position. This article aims to describe clinical considerations, applications, and results of palatal retractor use in clinical cases. Keywords: extraction treatment, anterior teeth retraction, palatal retractors, temporary anchorage devices.

T loop mechanics for effective space closure in bimaxillary dentoalveolar protrusion - A case report

This case report intends to highlight the space closure with continuous T-loop mechanics for bimaxillary protrusion. Loops can be fabricated in a sectional or full arch wire, and closing loops are usually used in loop mechanics for extraction space closure. The major advantage of loop mechanics is the lack of friction between the bracket and arch wire during space closure. A 21-year old adult male patient with bimaxillary protrusion and spacing reported to the clinic. The patient was treated successfully by maximum retraction of maxillary and mandibular anterior teeth after extraction of all first premolars. Space closure was achieved using a moment differential between posterior and anterior segments created by a T-loop. A stable result with normal over jet and overbite was achieved with retraction of maxillary and mandibular anterior teeth and no loss of anchorage.

Orthodontic Treatment of Severe Bimaxillary Dentoalveolar Protrusion with Skeletal Class II Malocclusion Without Using Miniscrews

Bimaxillary dentoalveolar protrusion is characterized by the proclined anterior teeth, protrusive lips, and a convex profile. A proper orthodontic treatment modality for efficient anchorage control is necessary to retract the anterior teeth and improve the facial esthetics significantly. The commonly used miniscrew could provide absolute anchorage, however, it is accompanied by some risks and complications, especially in adolescent females. This case report described a 16-year-old female with diagnosis of skeletal Class II, normal mandibular plane angle, and Angle Class I malocclusion associated with proclined upper and lower anterior teeth, excessive overjet, and a convex profile with lip incompetence. We extracted her four first premolars first. Then, the Tip-Edge Plus bracket system and differential force method were applied to replace the temporary anchorage device. The total treatment duration was 27 months. Her dentoalveolar protrusion was decreased, both lips were significantly retracted, the mentalis strain was reduced, and her chin projection was improved. This case demonstrated that differential tooth movement with controlled light orthodontic forces could be an effective strategy to treat severe bimaxillary protrusion.

Mini screws – An absolute anchorage for en-mass retraction of bimaxillary dentoalveolar protrusion: A case report

Mini screws – An absolute anchorage for en-mass retraction of bimaxillary dentoalveolar protrusion: A case report - JCO- Print ISSN No: - Online ISSN No:- 2582-0478 Article DOI No:- 10.18231/j.jco.2021.006, Journal of Contemporary Orthodontics-J Contemp Orthod

Three-Dimensional Digital Image Analysis of Skeletal and Soft Tissue Points A and B after Orthodontic Treatment with Premolar Extraction in Bimaxillary Protrusive Patients.

Aim. To investigate the effect of changes in incisor tip, apex movement, and inclination on skeletal points A and B and characterize changes in skeletal points A and B to the soft tissue points A and B after incisor retraction in Angle Class I bimaxillary dentoalveolar protrusion. Methods. Twenty-two patients with Angle Class I bimaxillary dentoalveolar protrusion treated with four first premolar extractions were included in this study. The displacement of skeletal and soft tissue points A and B was measured using cone-beam computed tomography (CBCT) using a three-dimensional coordinate system. The movement of the upper and lower incisors was also measured using CBCT-synthesized lateral cephalograms. Results. Changes in the incisal tip, apex, and inclination after retraction did not significantly affect the position of points A and B in any direction (x, y, z). Linear regression analysis showed a statistically significant relationship between skeletal point A and soft tissue point A on the anteroposterior axis (z). Skeletal point A moved forward by 0.07 mm, and soft tissue point A moved forward by 0.38 mm, establishing a ratio of 0.18: 1 (r = 0.554, p &lt; 0.01). Conclusion. The positional complexion of the skeletal points A and B was not directly influenced by changes in the incisor tip, apex, and inclination. Although the results suggest that soft tissue point A follows the anteroposterior position of skeletal point A, its clinical significance is suspected. Thus, hard and soft tissue analysis should be considered in treatment planning.

Proximity of upper central incisors to incisive canal among subjects with maxillary dentoalveolar protrusion in various facial growth patterns.

To investigate the position of the upper central incisor roots (U1) relative to the incisive canal (IC) among subjects with maxillary dentoalveolar protrusion in various facial growth patterns. 240 cone beam computed tomography images of skeletal Class I and II maxillary or bimaxillary protrusive subjects with a mean age of 23.74 ± 3.73 years were enrolled according to their facial growth pattern. The IC volume was measured using Mimics 21 software (Materialise, Leuven, Belgium). The U1 inter-root distance, width of IC, and their proximity were estimated using Invivo6 software (Anatomage, San Jose, CA). The IC volume was slightly greater among the high angle facial group and female patients than the other groups. Overall, the IC width was greater than the U1 inter-root distance in 55.65%, 57.6%, and 65% among the average, low, and high angle facial groups, respectively, and in 56.5% and 62.9% of males and females, respectively. The overall anteroposterior (sagittal) distances between the U1 roots and IC were 4.36 ± 1.18, 4.78 ± 1.17, and 3.83 ± 0.90 mm among the average, low, and high angle facial groups, respectively. The high angle facial group and female patients showed slightly greater IC dimensions than the other groups. The overall maximum sagittal distances between the U1 and IC were around 5.5, 6, and 4.7 mm among the average, low, and high angle facial groups, respectively. The low angle facial group and male patients tended to have greater sagittal distances. Therefore, the present findings could serve as a guideline when a considerable amount of upper incisor retraction is planned for Class I or II maxillary or bimaxillary dentoalveolar protrusion patients.

Le Fort I osteotomy with segmentation for the treatment of maxillary dentoalveolar protrusion: a single-centre, 10-year outcome study

A retrospective study was conducted to evaluate the stability and complications of Le Fort I osteotomy with segmentation for the treatment of bimaxillary dentoalveolar protrusion. A total of 120 consecutive patients who had undergone orthognathic surgery between 2008 and 2017 at a single centre were recruited. Lateral cephalometric radiographs were taken before surgery, within 6 weeks after surgery, and at 2 years after surgery. U1–SN and U1–PP underwent mean uprighting of 8.7° and 9.6°, respectively, and mean relapse of 2.1° and 2.6°, respectively (both P < 0.05). The only significant risk factor for relapse was the use of intermaxillary fixation (risk ratio (RR) 1.2, P = 0.01). The most common complication was wound dehiscence (41.7%), which was a significant risk factor for wound infection (RR 3.3, P < 0.01) and fixation hardware exposure (RR 3.7, P < 0.01). Other common complications were gingival recession (40.8%), periodontal bone loss (40%), and blood loss requiring transfusion (26.7%), the latter of which was associated with the preoperative diagnosis of vertical maxillary excess (RR 2.4, P = 0.01). Some degree of relapse occurred in more than 90% of the patients by 2 years after surgery. The procedure is not without risks and complications but may be useful in severe cases.