Protrusion Of Lower Incisors Research Articles

Evaluation of modified clear Twin Block aligner in treating adolescents with skeletal class II malocclusion: A two-centre cephalometric study.

The purpose of this study was to evaluate the therapeutic effect of modified clear Twin Block (CTB) aligner and traditional twin block (TB) appliance from skeletal, dentoalveolar and soft tissue changes in adolescents with skeletal class II malocclusion. A total of 80 adolescents, included in this study from two medical centres, were distributed into CTB group, TB group and control group based on the treatment they received. Lateral cephalograms at pre-treatment (T1) and post-treatment (T2) were measured by modified Pancherz's cephalometric analysis, and dentoskeletal and soft tissue changes were analysed by independent-sample t-test, paired-sample t-test, ANOVA test and Scheffe's Post Hoc test. Seventy-five adolescents completed the study, including 32 in the CTB group, 32 in the TB group and 11 in the control group. Both CTB and TB treatment showed significant differences in most dentoskeletal and soft tissue measurements. Compared with the control group, improvements were observed in class II molar relationship through significant different in S Vert/Ms-S Vert/Mi in the CTB group (P < .01) and the TB group (P < .001), as well as deep overjet through significant different in S Vert/Is-S Vert/Ii in the CTB group (P < .001) and the TB group (P < .001). Besides, the CTB group also showed less protrusion of lower incisors and resulted in a more significant improvement in profile with fewer adverse effects on speaking, eating and social activities. For adolescents with skeletal class II malocclusion, CTB appliance was as effective as TB on improving dentoskeletal and soft tissue measurements, featuring more reliable teeth control and patient acceptance.

Dentoskeletal and soft-tissue changes concurrent to use of PowerScope appliance in treatment of Class II malocclusion – A retrospective study

Objectives: The most frequently encountered malocclusion in our daily clinical practice is Class II malocclusion with mandibular retrognathism. Treatment modalities for Class II malocclusion correction depend on numerous factors such as the severity of the malocclusion and the age at which the patient reports for the treatment. One of the innovations in Class II treatment is the PowerScope appliance. The objectives of this study were: (1) To evaluate dentoskeletal changes with the use of PowerScope appliance in the treatment of Class II division I malocclusion using lateral cephalograms in late adolescents. (2) To evaluate the soft-tissue changes with the use of PowerScope appliance in the treatment of Class II division I malocclusion using lateral cephalograms in late adolescents. Materials and Methods: This retrospective and cross-sectional study was done using pre- and post-treatment lateral cephalograms of 15 patients treated with PowerScope appliance who were under decelerated growth phase as assessed by cervical vertebrae maturation index (Stages 4, 5, and 6). All the lateral cephalograms were hand traced and measured by same investigator. Results: A highly statistically significant difference was observed between the pre-and post-angle formed by sella nasion plane and nasion to point B line (SNB), angle formed by nasion to point A line and nasion to point B line (ANB), condylion to point gnathion (Co–Gn), and distance between point A to nasion perpendicular (N perpendicular to Point A) to Pog skeletal parameters. It was found that a highly significant difference was noted for parameters upper molar to palatal plane (U6-PP), lower incisor to nasion to point B line (L1-NB), lower incisor to nasion to point B line (L1-NB*), lower incisor to mandibular plane angle (IMPA), and upper molar to pterygoid vertical line (U6-PTV). A significant difference was present for parameters upper incisor to nasion to point A line (U1-NA), while no difference was observed for upper incisor to sella nasion plane (U1-SN) and upper molar to pterygoid vertical line (U6-PTV). A significant statistical difference was observed between the pre-and post-lower lip to E line parameter. Conclusion: PowerScope caused significant skeletal changes by forward repositioning of the mandible as well as by an increase in the length of the mandible. There was significant retrusion of upper incisors and a highly significant increase in lower incisor protrusion, lower molar mesialization, and upper molar intrusion. Soft-tissue lower lip protrusion was significant.

Automated diagnostic classification with lateral cephalograms based on deep learning network model

Objective: To establish a comprehensive diagnostic classification model of lateral cephalograms based on artificial intelligence (AI) to provide reference for orthodontic diagnosis. Methods: A total of 2 894 lateral cephalograms were collected in Department of Orthodontics, Capital Medical University School of Stomatology from January 2015 to December 2021 to construct a data set, including 1 351 males and 1 543 females with a mean age of (26.4± 7.4) years. Firstly, 2 orthodontists (with 5 and 8 years of orthodontic experience, respectively) performed manual annotation and calculated measurement for primary classification, and then 2 senior orthodontists (with more than 20 years of orthodontic experience) verified the 8 diagnostic classifications including skeletal and dental indices. The data were randomly divided into training, validation, and test sets in the ratio of 7∶2∶1. The open source DenseNet121 was used to construct the model. The performance of the model was evaluated by classification accuracy, precision rate, sensitivity, specificity and area under the curve (AUC). Visualization of model regions of interest through class activation heatmaps. Results: The automatic classification model of lateral cephalograms was successfully established. It took 0.012 s on average to make 8 diagnoses on a lateral cephalogram. The accuracy of 5 classifications was 80%-90%, including sagittal and vertical skeletal facial pattern, mandibular growth, inclination of upper incisors, and protrusion of lower incisors. The acuracy rate of 3 classifications was 70%-80%, including maxillary growth, inclination of lower incisors and protrusion of upper incisors. The average AUC of each classification was ≥0.90. The class activation heat map of successfully classified lateral cephalograms showed that the AI model activation regions were distributed in the relevant structural regions. Conclusions: In this study, an automatic classification model for lateral cephalograms was established based on the DenseNet121 to achieve rapid classification of eight commonly used clinical diagnostic items.

Comparison of skeletal and dentoalveolar effects of two different mandibular advancement methods: conventional technique vs aesthetic approach.

The aim of this study was to compare the effects of two different mandibular advancement methods on skeletal, dentoalveolar, and soft tissue structures through cephalometric measurements. The aim of this study was to compare the effects of two different mandibular advancement methods on skeletal, dentoalveolar, and soft tissue structures through cephalometric measurements. The mandibular base was observed to move forward significantly in both groups (p<0.05). However, the forward movement of the mandibular base was greater in the TB group than in the EA group (p<0.05). There was no difference in lower incisor protrusion between the two treatment methods. The EA device was found to cause a significant increase in vertical direction parameters (p<0.05). Both methods resulted in Class II malocclusion correction as well as an acceptable occlusion plus profile. The effects of EA were primarily dentoalveolar. In patients with high aesthetic expectations, EA could be an alternative for TB.

Comparação da posição do incisivo inferior na sínfise em jovens brasileiros leucodermas, xantodermas e nipobrasileiros com oclusão normal

Objective: To compare the linear and angular measurements using as a parameter the Vigorito analysis in Leucoderm, Xanthoderm, and Japanese-Brazilian people to obtain the average normal values, to compare the values obtained and the differences between groups and sex dimorphism. Material and Methods: The retrospective sample included 103 lateral films of young Brazilian people with normal occlusion. It was divided into three groups: Group I with 38 Leucoderm subjects, Group II with 33 Xanthoderm subjects, and Group III with 32 Japanese-Brazilian subjects. Lateral films were scanned using Scan Maker i800 scanner, and CephX 4.5.4. was used to measure the cephalometric variables specific to the analysis, and they were statistically compared. Age compatibility was analyzed using ANOVA test followed by Tukey test. Sexual dimorphism was evaluated with independent t test, and the intergroup comparisons were performed with ANCOVA followed by Tukey test. Results: Leucoderm and Japanese-Brazilian female group presented statistically significant differences for sexual dimorphism, showing a higher facial convexity and lower mandibular incisor less protruded. Besides that, Japanese-Brazilian subjects presented a significantly lower maxillary protrusion when compared to Xanthoderm and Leucoderm subjects. The latter group also had lower incisor protrusion when compared to Japanese-Brazilian and Xanthoderm, respectively. Conclusions: Leucoderm, Xanthoderm, and Japanese-Brazilian subjects with normal occlusion presented dentoskeletal, dental and facial differences, and gender differences related to the mandibular symphysis. Thus, the individualization of cephalometric patterns in different groups is justified.

Treatment of Skeletal CL II Patient with Maximum Lower Incisor Protrusion and Minimum Overjet with Rahhal Functional Appliance

Treatment of skeletal Cl II includes functional orthopedic treatment, head-gears, extraction of the upper premolars and orthognathic surgery. To treat any patient with functional appliances (bite jumping) an adequate overjet is necessary. In this case an 11 years old female patient has skeletal CLII due to mandibular deficiency with ANB angle 8 degrees, overbite: 3 mm, overjet: 1 mm, extremely convex profile and underdeveloped chin due to the hyper muscle contraction of the lower lip to obtain oral seal. To obtain an adequate overjet lower first premolars were extracted and maximum retraction using mini screws (for maximum anchorage) was applied. Afterwards Rahhal functional appliance was used by the patient 16 hours a day for 6 months and 10 hours a day for another 6 months for retention. After that fixed orthodontic treatment was completed. Lateral cephalometrics were taken, traced and analyzed. In the result Skeletal CLI was obtained (ANB 4 degree), straight facial profile, normal over bite overjet and particular chin development were noticed. As a conclusion, in skeletal CLII malocclusions, lower incisor protrusion will cause a contraindication for functional treatment. Extraction of the lower premolars and retraction of the lower incisors followed by functional orthopedic treatment is an efficient method to treat these cases instead of waiting for orthognathic surgery, also reducing the muscle pressure on the chin will change the development characteristics of it.

The Impact of Extraction vs Nonextraction Treatment on Soft Tissue Profile in Borderline Class I Malocclusion: A Cephalometric Study

Introduction: The continuous controversy concerning extraction of premolar teeth and its supposed effects on the facial profile led to the origin of this study, which compares the pretreatment and post-treatment facial profiles of patients who underwent premolar extraction with those of patients who did not undergo extraction. Objective: To analyze the soft tissue changes between the two different treatment groups, equally susceptible to both treatment options (extraction and nonextraction) and to compare the changes taking place in the soft tissue variables from one group to another using the cephalometric analysis. Materials and methods: The diagnostic extraction and treatment decisions were based on a total space analysis with differential extraction protocols. The pretreatment and posttreatment cephalograms of the borderline sample (100 female patients, 50 of the patients were treated with premolar extraction and 50 were treated without premolar extraction) were then subjected to a thorough soft tissue cephalometric analysis. Results: The results indicated that the three variables that played the most important role in the clinician’s treatment decision were indicators of lower crowding, soft tissue convexity and lower incisor protrusion. Significant differences (p < 0.05) regarding upper and lower lip protrusion, upper lip thickness (p < 0.05) and the nasolabial angle (p < 0.05) occurred after treatment. Conclusion: Extraction treatment of Class I borderline malocclusions led to significant soft tissue changes in relation to the upper and lower lip position and thickness as well as the nasio labial angle, whereas the nonextraction treatment resulted in significant upper lip retraction and lower lip protraction.

Changes in soft tissue profile following the treatment using a Herbst appliance: A photographic analysis

Aesthetics is the reason for most of the class II malocclusion patients to opt for orthodontic treatment. In order to regulate retrognathic profile Herbst appliance for anterior movement of the mandible can be a treatment of choice. The aim of this study was to determine the soft tissue profile changes following Herbst appliance therapy on before and after treatment photos, using the computer program. This investigation was performed on profile photographs of 20 class II patients (12 females and 8 males) aged 18-23 years. Analysis of the changes in soft tissue facial structure relationships evident on the photographs before and after the Herbst appliance therapy was performed using Bentley Micro Station program. The first contour of the soft tissue profile was marked. The following reference lines were subsequently traced: Ricketts aesthetic E line and Juanita line. The area enclosed by these two lines included the nose, upper and lower lip, chin and free space in front of the lips. Using the computer program, the surfaces of the soft tissue structures and free space defined by the reference lines and profile contours were measured. Calculation of the relative proportion of surfaces was done for each photograph. The data obtained were then compared for each patient before and after the treatment. Skeletal and dentoalveolar treatment effects that support soft tissue changes were presented by the profile cephalometric parameters of sagital occlusion (SO) analysis. A reduction in the relative surface of the upper lip in males (p < 0.01) and females (p < 0.05) was shown by the pictures. The space occupied by the chin was reduced after the treatment for females only (p < 0.05). The relative surface of the nasal soft tissues, that was included in the reference space was increased (p < 0.01) in both genders. The relationship between the soft tissue and empty surface was changed in favor of the empty surface (p < 0.05) in females. No statistically significant differences were found between the males and the females, before or after the Herbst appliance therapy. The soft tissue changes were the consequence of skeletal and dentoalveolar treatment effects: upper incisors retrusion, lower incisor protrusion and forward movement of the lower jaw. The Herbst appliance therapy caused a significant improvement of the profile appearance. The extent of soft tissue changes that occur on its dentoalveolar and skeletal support is a complex issue.

Effects of mandibular protraction appliance associated to fixed appliance in adults

This retrospective study aimed to conduct a cephalometric evaluation of the skeletal, dental and soft tissue effects resulting from treatment of adult patients presenting Class II malocclusion, performed with a Mandibular Protraction Appliance (MPA) combined with a fixed orthodontic appliance. The sample consisted of teleradiographs obtained before and after treatment of 9 adult patients (initial mean age of 22.48 years) with bilateral Class II, division 1, malocclusion. Paired t test (p < 0.05) was applied to compare initial and final values. t test revealed an increase in anteroinferior facial height and posterior facial height. The dental changes include: extrusion of upper incisors, buccal inclination, protrusion of lower incisors, mesialization and extrusion of mandibular molars. Regarding the soft tissue component, there was an increase in nasolabial angle in addition to upper lip retrusion. The effects of treating Class II malocclusion adult patients, by means of using Mandibular Protraction Appliance (MPA) combined with a fixed appliance were mostly observed in the mandibular arch, and consisted of buccal inclination, protrusion and intrusion of incisors, and mesialization and extrusion of the molars.

Dentoskeletal effects of Twin Block and Herbst appliances in patients with Class II division 1 mandibular retrognathy

The aim of this study is to evaluate dentoskeletal effects of Herbst and Twin Block (TB) appliance therapies in Skeletal Class II malocclusion. Herbst group consisted of 11 girls and 9 boys (mean age = 12.74 ± 1.43 years), TB group comprised of 10 girls and 10 boys (mean age = 13.0 ± 1.32 years), and control group included 9 girls and 11 boys (mean age = 12.17 ± 1.47 years). Mean treatment/observation times were 15.81 ± 5.96 months for Herbst, 16.20 ± 7.54 months for TB, and 15.58 ± 3.13 months for control group. Pre-treatment (T0) and post-treatment (T1) lateral cephalograms were traced using a modified Pancherz's cephalometric analysis. Inter-group differences were evaluated with one-way analysis of variance, and intra-group differences were assessed with paired samples t-test at the P < 0.05 level. In control group, all sagittal and vertical skeletal measurements increased as a result of continuing growth. However, skeletal discrepancy and overjet remained unchanged. After functional appliance therapy, greater increases were recorded in TB group for all mandibular skeletal measurements compared with those in control group. Upper dental arch distalization and lower incisor protrusion were significant in Herbst group, compared with control. All face height measurements increased after functional appliance therapy. In TB group, the treatment effects were mainly due to mandibular skeletal changes. Both skeletal and dental changes contribute to Class II correction with Herbst appliance therapy. Herbst appliance may be especially useful in Skeletal Class II patients with maxillary dentoalveolar protrusion and mandibular dentoalveolar retrusion, whereas TB appliance may be preferred for skeletal mandibular retrognathy patients.

Alveolar bone thickness and lower incisor position in skeletal Class I and Class II malocclusions assessed with cone-beam computed tomography

ObjectiveTo evaluate lower incisor position and bony support between patients with Class II average- and high-angle malocclusions and compare with the patients presenting Class I malocclusions.MethodsCBCT records of 79 patients were divided into 2 groups according to sagittal jaw relationships: Class I and II. Each group was further divided into average- and high-angle subgroups. Six angular and 6 linear measurements were performed. Independent samples t-test, Kruskal-Wallis, and Dunn post-hoc tests were performed for statistical comparisons.ResultsLabial alveolar bone thickness was significantly higher in Class I group compared to Class II group (p = 0.003). Lingual alveolar bone angle (p = 0.004), lower incisor protrusion (p = 0.007) and proclination (p = 0.046) were greatest in Class II average-angle patients. Spongious bone was thinner (p = 0.016) and root apex was closer to the labial cortex in high-angle subgroups when compared to the Class II average-angle subgroup (p = 0.004).ConclusionsMandibular anterior bony support and lower incisor position were different between average- and high-angle Class II patients. Clinicians should be aware that the range of lower incisor movement in high-angle Class II patients is limited compared to average- angle Class II patients.

The impact of extraction vs nonextraction treatment on soft tissue changes in Class I borderline malocclusions

To obtain through the use of discriminant analysis a relatively bias-free sample of extraction and nonextraction, Class I, equally susceptible to both treatments' malocclusions and to analyze retrospectively the soft tissue changes between the two different treatment groups. The cephalometric, model, and demographic data of 215 patients (females and males) fueled a stepwise discriminant analysis that provided the borderline homogenous subsample (30 extraction and 32 nonextraction cases). The pretreatment and postreatment cephalograms of the borderline sample were then subjected to a thorough soft tissue cephalometric analysis. The results indicated that the three variables that played the most important role in the clinician's treatment decision were indicators of lower crowding, soft tissue convexity, and lower incisor protrusion. Significant differences (P < .001) regarding upper and lower lip protrusion, upper lip thickness (P < .05), and the nasiolabial angle (P < .05) occurred. Extraction treatment of Class I borderline malocclusions led to significant soft tissue changes regarding the upper and lower lip position and thickness as well as the nasiolabial angle, whereas the nonextraction treatment resulted in significant upper lip retraction and lower lip protraction.

Dentoskeletal Effects and “Effective” Temporomandibular Joint, Maxilla and Chin Changes in Good and Bad Responders to van Beek Activator Treatment

To assess possible differences in dentoskeletal effects and "effective" temporomandibular joint, maxilla, and chin changes between good and bad responders to van Beek activator treatment. The subject material consisted of 20 consecutive normodivergent male Class II division 1 patients treated with a van Beek activator. Because of insufficient cooperation, four patients were excluded. Lateral head films were taken 6 months before treatment, at start of treatment, and after 12 months of treatment. The patients were placed into a good responder group (successful, n = 8) and a bad responder group (unsuccessful, n = 8). An overjet reduction > or =4 mm was considered successful. During the van Beek treatment period, the good responders showed a significantly larger improvement in overjet and molar relationship than did the bad responders. The good responders exhibited a significant posterior development of condylion, less anterior mandibular autorotation, retrusion of upper incisors, protrusion of lower incisors, distalization of maxillary molars, and a mesial movement of mandibular molars. No significant dental movements were seen in the bad responders. Although van Beek activator treatment affected the direction of condylar growth, as well as the direction of maxilla and chin changes, it can be concluded that skeletal changes did not contribute to the Class II correction. Instead, overjet reduction during van Beek activator treatment was found to be due to a favorable dental reaction.

The influence of functional orthodontics and mandibular sagittal split advancement osteotomy on dental and skeletal variables--a comparative cephalometric study

Lateral head films of 200 Class II patients (106 females, 94 males) with a mean pre-treatment age range of 9.9-10.25 years successfully treated with functional orthodontics were analysed before (T1) and after (T2) treatment. The resulting data and findings were compared with lateral head films (T1, T2) of 20 patients (15 females, five males) with a mean pre-treatment age of 25.75 years whose Class II malocclusion and antero-posterior jaw discrepancy had been corrected by a mandibular sagittal split advancement osteotomy. The median and interquartile distances were calculated for every variable, at T1 and T2. The difference between the medians (T2-T1) was analysed using a signed rank test. The changes in scattering (T2-T1) were assessed by means of a F-test. Significant differences regarding the therapeutic influence on skeletal [ANB, Wits, Index, mandibular line-nasal line (ML-NL)], functional (beta', mu), and dental (1-NA degrees , 1-NB degrees ) variables were found. In the group initially treated with functional appliances in order to enhance mandibular prognathism, the antero-posterior (A-P) jaw discrepancy was reduced (ANB, Wits). The vertical skeletal pattern (Index) changed towards a more skeletal open relationship, whereas the ML-NL angle was reduced, which indicates a deepening of the bite. The comparison between biomechanical incisor position analysis (beta', mu) and dental variables (1-NA degrees , 1-NB degrees ) revealed different changes in incisor inclination depending on the type of analysis used. The findings for the dental variables (1-NA degrees , 1-NB degrees ) showed a protrusion of both upper and lower incisors after therapy. The results for the functional variables (beta', mu) showed a retrusion of the upper and a protrusion of the lower incisors. This change in incisor inclination is a dental compensation of the remaining sagittal jaw discrepancy. This effect is most clearly reflected by the functional analysis and the changes of the biomechanical variables beta' and mu. For the orthognathic surgery group, a clear improvement in the dental and skeletal relationship was observed: the skeletal discrepancies in the A-P plane were completely corrected (ANB, Wits) and the inclination of the incisors according to biomechanical and functional aspects was optimized (beta', mu).The alteration in both the Index and ML-NL angle in this group indicated an increase of the open bite components.

Is it necessary to treat incisal protrusion in Tunisian children?

It is thought that incisor protrusion could be ethnic-related because Tunisians, as Africans, might reflect the genetic influence of the incisal protrusion of their darker skinned neighbors. We first compiled local standards by determining the normal incisor positions of children of the Sfax region with balanced facial patterns. We selected 95 teenagers from 5 different high schools in Sfax (average age: 16 years 9 months), all having a normal dentition and a balanced facial pattern. This first study showed that upper and lower incisors were protruded 3 mm beyond American standards. Second, we studied incisor stability after four-first bicuspid extraction treatment. We selected 26 patients all having Class I molar relationships and upper and lower incisor protrusion. We compared x-ray incisor measurements of 3 radiographs: before treatment, after treatment and 2 or 3 years post-treatment. This study shows that incisor relapse ranges between 20 and 30%.

A formula to determine the amount of retraction of mandibular canines.

Moderate to severe protrusion of anterior teeth often necessitates the extraction of 4 premolars to retract anterior teeth into their space. We present a formula that determines how far the mandibular canines should be retracted to provide adequate space for correction of lower incisor protrusion. To test the accuracy of the formula, 23 mandibular setups were made and the results of the formula were compared with those of the setups. Paired t-tests at a confidence level of 95% did not show any statistically significant differences between the results.