Factors affecting unusual postoperative vertical downward movement of mandible after surgery-first approach using intraoral vertical ramus osteotomy.

BACKGROUND: In very rare cases, patients who have undergone surgery-first approach with intraoral vertical ramus osteotomy (IVRO) exhibit unusual downward movements of mandible even up to 1-year post surgery, which makes it difficult for orthodontists to stabilize the occlusion during the postoperative orthodontic period. The aim of this study was to identify factors affecting the unusual downward movement of the mandible 1-year after the surgery-first approach using IVRO, while focusing on cephalometric values. METHODS: This retrospective cohort study sample was divided into two groups based on the amount of vertical movement of the B-point 1-year post surgery (Group S, predictable upward movement; Group U, unpredictable downward movement greater than 2 mm). To evaluate cephalometric changes between the two groups, cephalograms were obtained before surgery, 1 day after surgery, 1 month after surgery, and 1 year after surgery. The data were analyzed using the independent t-test, Mann-Whitney U test with Bonferroni correction, Pearson correlation analysis, and multiple regression analysis. RESULTS: At the initial examination, Group U showed a shallower anterior overbite. The vertical surgical change in the B-point was statistically different between the two groups (p < 0.001), indicating that group U exhibited more upward movement of the mandible during surgery. Group U showed significant downward movement of the mandible 1 month after surgery, and this finding persisted until 1 year postoperatively. Clockwise rotation of the mandible was also observed. Surgical vertical movement of the B-point showed a strong correlation with postoperative vertical movement of mandible (r = -0.674; p < 0.001) along a linear relationship, indicating that the amount of postoperative vertical downward movement of the mandible increased as the amount of surgical upward movement of the B-point increased (R2 = 0.449; p < 0.001). CONCLUSIONS: This study revealed that unusual downward movement of the mandible after a surgery-first approach using IVRO is correlated with the amount of upward movement during the surgery. When planning surgery, in cases in which a significant upward movement of the mandible is anticipated, orthodontists should prepare for the possibility of subsequent unusual downward movement and a tendency for the anterior overjet to decrease during the postoperative orthodontic period.

Evaluation of anterior teeth crown-root morphology and alveolar bone structure in patients with closed deep overbite using cone beam computed tomography.

This retrospective study used cone-beam computed tomography to investigated the crown-root morphology and alveolar bone structure in incisors region in subjects with closed deep overbite and comparison the difference between gender and age. The CBCT images for 40 subjects (group C) with Angle II division 2 were selected from patients of the HeFei Stomatological Hospital from November 2023 to March 2024.20 individual normal occlusion subjects (group A),20 patients with Angle II division 1(group B) were included. The crown-root ratio of the maxillary and mandibular anterior teeth, crown-root angle and alveolar bone structure were measured on the CBCT images, the data were statistically analyzed. In addition to mandibular lateral incisor, the crown-root ratio of maxillary and mandibular anterior teeth in the Class II division 2 group was higher than that in the individual normal occlusion group and the Class II division 1 (P < 0. 05). The crown-root angle of maxillary anterior teeth in the Class II division 2 group was smaller than that in the individual normal occlusion group and the Class II division 1 (P < 0. 05). The alveolar bone thickness of the maxillary central incisor was comparatively smaller, while the alveolar bone height was relatively higher in the Class II division 2 group. Age and gender were associated with change in root lengths and crown-root angle for the Class II division 2 group (P < 0. 05). Patients with closed deep overbite malocclusion exhibit a significant difference compared to the controls for most measurements. The patients presenting with Class II division 2 malocclusion exhibit excessive inward positioning of the anterior teeth, resulting in evident crown-root angle, a large crown-root ratio, and minimal labial alveolar bone. In order to keep the tooth movement within the safe range of alveolar bone movement, it is necessary to strictly control the torque and use appropriate orthodontic force to reduce the risk of bone fenestration, bone dehiscence, gingival recession and root resorption.

Evaluation of dentoalveolar changes following maxillary incisor intrusion with one vs two anterior miniscrews in subjects with gummy smile: a randomized clinical trial.

OBJECTIVES: To examine dentoalveolar changes following intrusion of maxillary incisors with one or two anterior miniscrews in subjects with gummy smile and deep bite. MATERIALS AND METHODS: Forty-three subjects were selected and divided into two groups: group I (22 subjects: 15 women, 7 men; mean age 30 ± 10 years) received one miniscrew between the upper central incisors, and group II (21 subjects: 16 women, 5 men; mean age 30 ± 10 years) received two miniscrews between the canines and lateral incisors. Dentoalveolar parameters, including amount of intrusion, root resorption, incisor inclination, alveolar bone thickness, and buccal alveolar crest height (cementoenamel junction to labial alveolar crest), were evaluated using cone-beam computed tomography scans obtained before and after intrusion. The intergroup comparison was analyzed using a paired t-test and unpaired t-test to determine significant changes within and between groups. RESULTS: The amount of intrusion was significantly greater in group II than in group I (P < .05). No statistically significant differences were found between groups I and II for changes in incisor inclination, labial bone thickness, and buccal alveolar crest height (P > .05). CONCLUSIONS: Maxillary central and lateral incisor intrusion was significantly greater in subjects treated with two miniscrews. Root resorption of the maxillary central incisors was notably greater in subjects with one miniscrew, while maxillary lateral incisor resorption was greater in subjects treated with two miniscrews.

Influence of Invisalign precision bite ramp utilization on deep bite correction and root length in adults.

OBJECTIVES: To assess the influence of Invisalign precision bite ramp use on skeletal deep overbite correction and root length and volume of maxillary anterior teeth. MATERIALS AND METHODS: This was a retrospective study of 60 adults with skeletal deep overbite. Patients were divided into three groups: Invisalign (Align Technology, San Jose, Calif) with precision bite ramps (Invisalign with Bite Ramps [IBR] = 12), Invisalign with no bite ramps (INBR = 22), and full-fixed appliances (FFA = 26). Cone beam computed tomography records at T1 (pretreatment) and T2 (posttreatment) were used to measure eight skeletal, nine dental, and three soft-tissue cephalometric variables. Maxillary anterior teeth root length (mm), root volume (mm3), and percent root volume loss between T1 and T2 (%) were also recorded. RESULTS: Significant changes from T1 to T2 among the three groups were seen in ANB(o), lower face height (%), ODI (overbite depth indicator) (o), and U1-SN (o). Reduction in root length was significantly less (P < .001) in the INBR and IBR groups compared to the FFA group. Reduction in root volume and percent volume loss were significantly higher in the INBR group compared to the IBR group (P < .001), but the difference between the two Invisalign groups and the FFA group was not significant. CONCLUSIONS: Skeletal deep overbite correction using Invisalign with or without bite ramps is comparable to FFA. Reduction in root length was significantly less with Invisalign compared to FFA. Bite ramps influenced root volume and volume loss but not root length.

Digital analyses of Bolton tooth size ratios and their association to gender, angle class, and other occlusal traits: a study using a partially automated digital 3D model analysis.

BACKGROUND: This study aims to verify Bolton's values for tooth size ratios and to evaluate possible relationships to different occlusal traits using precise digital measurement methods. MATERIALS AND METHODS: Including 1000 consecutively selected patients from three study centres a digital, partially automated model analysis was performed utilizing the software OnyxCeph. The measurements comprised tooth width for calculation of anterior (AR) and overall ratio (OR) as a percentage, arch width, length, perimeter, overjet, overbite, space analysis in millimetre and the assessment of the angle classification. RESULTS: AR and OR were significantly increased compared to Bolton's ratios of 77.2% (AR) and 91.3% (OR). In the gender comparison, male patients showed larger tooth size ratios, especially in the OR. Patients with Angle Class II/1 and II/2 had smaller tooth size ratios than patients with Angle Class III and I. Thus, patients with Angle Class II/1 had the largest tooth diameters in all maxillary teeth and with Angle Class II/2 the smallest tooth sizes in the mandible. The largest tooth widths in the lower jaw were observed in the Angle Class III patient group. Furthermore, a negative correlation from AR/OR to overjet, overbite, and available space in lower jaw as well as a positive correlation to available space in upper jaw was detected. CONCLUSIONS: There is a clear correlation between the tooth size ratios and the present dysgnathia as well as other orthodontically relevant occlusal traits. This prior knowledge about our patients is extremely important to create an individualized treatment plan and enable sufficient occlusion. To achieve a functionally good occlusion with correct overjet and overbite, it is essential that the maxillary and mandibular teeth are proportional in size. Any deviation from the ideal patient in terms of tooth size, number, shape, or arch must be considered in the pre-therapeutic treatment plan in combination with the existing dysgnathia in order to be able to achieve a stable anterior and posterior occlusion with appropriate adjustments to the therapy post-therapeutically.

Nonsurgical synergistic full-arch vertical intrusion treatment of bimaxillary protruded hyperdivergent skeletal Class II malocclusion using aligners.

A bone-borne full-arch vertical control strategy using miniscrews was deployed with aligners to treat a case of skeletal hyperdivergent Class II malocclusion with bimaxillary protrusion. Miniscrews were inserted in the posterior buccal and palatal regions and the anterior buccal region of the maxilla to distribute vertical intrusive force through the upper arch by anchoring vertical elastics from the miniscrews to the aligners. Synergetic lower anterior intrusion was completed using bilateral posterior miniscrews to counteract the extrusive force generated. Substantial full upper arch and lower anterior vertical intrusion was achieved. In conjunction with en masse anterior-posterior retraction, synergetic posterior and anterior vertical intrusion facilitated counterclockwise rotation of the mandible, creating significant esthetic improvement. Anterior vertical elastics also provided flaring of the anterior teeth, reducing the side effect of lingual tipping from en masse retraction, while successfully controlling overbite and incisor torque during space closure. The bone-borne full-arch vertical intrusion strategy can work well with aligners to address hyperdivergent skeletal Class II malocclusion with bimaxillary protrusion.

Prevalence and nature of bullying in schoolchildren aged 10-14 years and its association with malocclusion: A cross-sectional study in the South East of the UK.

OBJECTIVE: To investigate the prevalence of, and relationship between, bullying and malocclusion in schoolchildren aged 10-14 years in the South East of the UK. DESIGN: Cross-sectional cohort study. SETTING: Sixteen primary and secondary schools in South East of the UK. PARTICIPANTS: Schoolchildren aged 10-14 years who were consented to participate. METHODS: The prevalence and nature of bullying were measured using a questionnaire. Traits of malocclusion and the need for orthodontic treatment were assessed by clinical examination and determined by the Index of Orthodontic Treatment Need (IOTN) Dental Health (DHC) and Aesthetic components (AC). RESULTS: Complete data were collected for 698 participants. The number defined as being bullied was 68 (9.7%). There was no difference in the prevalence of bullying between gender, ethnicity or age. Higher rates of bullying were reported in mixed sex schools (P = 0.03). Participants with an increased overjet (P = 0.02) and/or a greater need for treatment, as measured by IOTN DHC (P = 0.01) and AC (P = 0.01), reported higher rates of bullying. While there was no difference in the overall prevalence of bullying between genders, boys were more likely than girls to experience physical bullying (P <0.001) and being called names (P = 0.03). CONCLUSION: A significant relationship was evident between being bullied and certain traits of malocclusion.

A Systematic Method for a Full-Mouth Rehabilitation of a Dentition With Extensive Overjet and Occlusal Dysfunction.

A patient presented desiring to improve her esthetics and reduce masseter muscle pain prior to her upcoming wedding. Although the patient had a full-mouth rehabilitation with porcelain restorations at age 16, she presented with extensive overjet, unbalanced occlusion, and lack of contact from premolar to premolar. The clinician was faced with the challenge of determining the best course of treatment. After completing thorough record-taking and a detailed analysis following a systematic approach, the clinician developed a facially driven treatment plan that was carried out over eight phases. The patient's existing crowns were replaced at a reduced vertical dimension of occlusion, esthetics were enhanced, muscle pain was relieved, and her goals were achieved.

Relación del plano oclusal con la altura del ángulo goníaco y proyección del mentón / Relation of the occlusal plane with the height of the gonial angle and projection of the chin

Introducción: hemos observado en nuestra práctica ortodóncica una gran cantidad de pacientes con plano oclusal inclinado, con un ángulo goníaco alto y postero-rotación mandibular. Todo parece indicar que el plano oclusal juega un papel muy importante en el desarrollo de las maloclusiones. Objetivo: mostrar en el presente caso clínico de un niño, si existe una correlación entre la inclinación del plano oclusal, la altura del ángulo goníaco, la longitud de la rama mandibular y la proyección del mentón antes y después, al corregirlo y hacerlo más horizontal con tratamiento ortodóncico. Caso clínico: paciente masculino de 11 años de edad, hiperdivergente, clase II esquelética severa, perfil convexo, apiñamiento dental superior e inferior, clase II molar, incompetencia labial severa, mordida profunda, overjet aumentado, mentón retrusivo, cervicales rectificadas y anterorotación de cabeza. El tratamiento de ortodoncia se realizó con brackets Roth slot 22 y extracciones de primeros premolares superiores e inferiores y primeros molares superiores (siendo reemplazados por los terceros molares superiores), curvas inversas, cierre de espacios con pérdida de anclaje y ajuste oclusal. Resultados: al finalizar el tratamiento, se logró mejorar la estética facial, un ángulo goníaco más desarrollado con mayor crecimiento vertical, mayor proyección del mentón, un plano oclusal más horizontal, un adecuado overbite y overjet, clase I molar y canina, antero-rotación mandibular, buena intercuspidación, oclusión funcional y excelente estabilidad oclusal sin retención, mejoría en lordosis cervical y posición de la cabeza. Conclusiones: la corrección de un plano oclusal inclinado en niños y adolescentes hiperdivergentes, puede mejorar de manera importante el vector de crecimiento, ayudar a un mayor desarrollo en la altura del ángulo goníaco y longitud de la rama mandibular, proyección del mentón al corregirlo y hacer el plano oclusal más horizontal con la mecánica ortodóntica de curvas inversas; por lo tanto, en el presente caso clínico: sí existe una correlación muy importante entre la inclinación del plano oclusal, la altura del ángulo goníaco y la proyección del mentón antes y después del tratamiento ortodóncico (AU)

Introduction: we have observed in our orthodontic practice a large number of patients with inclined occlusal plane, with a high goniac angle and posterior mandibular rotation. Everything seems to indicate that the occlusal plane plays a very important role in the development of malocclusions. Objective: to show in the present clinical case of a child, if there is a correlation between the inclination of the occlusal plane, the height of the goniac angle, the length of the mandibular branch and the projection of the chin before and after, when correcting it and making it more horizontal with orthodontic treatment. Case report: an 11 year old male patient, hyperdivergent, severe skeletal class II, convex profile, upper and lower dental crowding, molar class II, severe labial incompetence, deep bite, increased overjet, retrusive chin, rectified cervicals, and anterorotation of the head. Orthodontic treatment was performed with Roth slot 22 brackets and extractions of upper and lower first premolars and upper first molars (being replaced by upper third molars), inverse curve, space closure with loss of anchorage and occlusal adjustment. Results: at the end of the treatment, it was possible to improve facial aesthetics, a more developed gonial angle with greater vertical growth, greater chin projection, a more horizontal occlusal plane, an adequate overbite and overjet, molar and canine class I, mandibular anterorotation, good intercuspidation, functional occlusion and excellent occlusal stability without retention, improvement in cervical lordosis and head position. Conclusions: the correction of an inclined occlusal plane in hyperdivergent children and adolescents can significantly improve the growth vector, help further development in the height of the gonial angle and length of the mandibular ramus, chin protection when correcting it and making the most horizontal occlusal plane with the orthodontic mechanics of inverse curves; therefore, in the present clinical case: there is a very important correlations between the inclination of the occlusal plane, the height of the gonial angle and chin projection before and after orthodontic treatment (AU)

Effectiveness of removable anterior bite planes with varied mealtime protocols in correcting deep bites among growing patients: a randomized clinical trial.

OBJECTIVES: To compare effectiveness of two protocols for correcting deep bite in growing patients using a removable anterior bite plane (RABP): full-time wear with appliance on during meals (F + M) vs off during meals (F - M) and to explore the relationship between average daily duration of wear and overbite (OB) correction rate, stratified by the wear protocol. MATERIALS AND METHODS: Thirty-two growing patients with deep bite (mean age = 10.94 ± 2.17 years) were randomly assigned to the F + M (n = 16) or F - M (n = 16) group. Cephalometric radiographs were taken at baseline (T0) and when normal OB was achieved (T1). Duration of wear was recorded by a TheraMon microsensor within the appliance. A best-fit regression model for the relationship between daily duration of wear and OB correction rate was determined (α = 0.05). RESULTS: Both groups exhibited similar baseline characteristics and cephalometric changes, ie, molar extrusion, and incisor intrusion and proclination in both arches (P < .05), and intergroup differences were not significant. Here, F + M exhibited significantly faster rates of deep bite correction (1.83 ± 1.18 vs 1.08 ± 0.62 mm/month; P < .05) and mandibular molar extrusion (0.46 ± 0.25 vs 0.30 ± 0.18 mm/month, P < .05) compared with F - M. Best-fit regression models for relationship between daily duration of wear and OB correction rate were exponential for both F + M (R2 = 0.53) and F - M (R2 = 0.74). CONCLUSIONS: Here, F + M and F - M protocols resulted in comparable cephalometric changes among deep bite growing patients. However, the F + M group exhibited a faster correction rate. Daily duration of wear positively correlated with OB correction rate in an exponential manner.

[Comparison of the application of micro-implant screw support and flat guide plate in the treatment of excessive deep overbite of lower anterior teeth].

PURPOSE: To compare and analyze the orthodontic effects of micro-implant screw support and flat guide plate on excessive deep overbite of lower anterior teeth. METHODS: Eighty-two patients with excessive deep overbite of the lower anterior teeth who were treated from January to December 2022 were selected and randomly divided into two groups (41 in each group) by random number table method. Both groups were treated with straight wire arch orthodontic technology, and the anterior teeth were supported by micro-implant screws (micro-implant screw group) and flat guide plates (flat guide plate group), respectively. The effect of upper anterior tooth compression, changes in occlusal plane, and apical absorption were compared between the two groups. SPSS 25.0 software package was used for statistical analysis. RESULTS: There were no significant changes in SNA angle, SNB angle, ANB angle, U1-PP, U6-PP, and L6-MP before and after treatment between the two groups (P＞0.05). L1-MP significantly increased in both groups after treatment than before treatment(P＜0.05). There was no significant difference in bite opening, Spee curve depth, U1 depression, L1 depression, U6 elongation, L6 elongation and occlusal opening time between the two groups before and after treatment(P＞0.05). The root apex absorption of the mandibular central incisors and lateral incisors in the micro-implant screw group was significantly lower than that in the flat guide plate group(P＜0.05), while there was no significant difference in root apex absorption between the two groups of canines(P＞0.05). CONCLUSIONS: Both micro-implant screw support and flat guide plate can effectively lower the mandibular anterior teeth in the treatment of deep overbite in adults, with good orthodontic effects. However, the latter can lead to increased root resorption.

[Improvement of the mastication function of orthodontics combined with restoration in the treatment of deep overbite with severe lower anterior teeth attrition].

PURPOSE: To observe the effect of orthodontics combined with restoration on masticatory function in deep overbite patients with severe lower anterior teeth attrition. METHODS: From January 2018 to January 2022, a total of 164 deep overbite patients with severe lower anterior teeth attrition were collected and divided into two groups according to different treatment plans: control group(72 patients, with restoration treatment) and experimental group(92 patients, with orthodontics combined with restoration treatment). The chewing efficiency of the two groups was evaluated, temporomandibular joint dysfunction index (DI), muscle palpation index (PI) and cranio-mandibular index (CMI) were calculated. The satisfaction with facial esthetic, the Chinese version of Oral Health Impact Scale-14(OHIP-14) and the repair satisfaction score were evaluated, the occurrence of adverse events between the two groups was compared. SPSS 23.0 software package was used for statistical analysis. RESULTS: After treatment, the chewing efficiency of the experimental group was significantly improved compared to the control group, while the DI, PI, and CMI were significantly reduced compared to the control group(P＜0.05). Compared with the control group, the satisfaction degree with facial esthetic and restoration in the experimental group was significantly higher, while the OHIP-14 score was significantly lower after treatment(P＜0.05). The incidence of adverse events in the experimental group was significantly decreased compared with the control group (6.52% vs 25.00%, P＜0.05). CONCLUSIONS: Combination of orthodontics and restoration treatment can enhance the effectiveness of restoration treatment for deep overbite with severe lower anterior teeth attrition, improve the mastication function and temporomandibular joint balance,satisfaction and quality of life of patients, as well as reduce the risk of adverse events.

Evaluating malocclusion patterns in children with autism spectrum disorder using the index of complexity, outcome and need: a cross-sectional study.

BACKGROUND: The purpose of this study was to evaluate the complexity of malocclusion and existing patterns in children with autism spectrum disorders (ASD) using the index of complexity, outcome and need (ICON). METHODS: This cross-sectional study included children diagnosed with ASD, aged 9-15 years. A group of healthy children with the same demographic characteristics was randomly selected as the control group. Malocclusion was assessed according to ICON scoring protocol. The following parameters were recorded: dental aesthetics, upper arch crowding/spacing, presence of crossbite, anterior-vertical relationship (open and deep bite) and buccal segment anterior-posterior relationship. Finally, an overall ICON score was derived and reported for each patient. Descriptive analysis was performed for all investigated variables. Significance level was set at p < 0.05. RESULTS: A total of 324 children, divided into ASD (162) and control (162) groups, comprised the study population. Our results demonstrated that the average overall ICON score was significantly higher in the ASD group compared to the control group (38.77 vs. 27.43, p < 0.001). ASD children also obtained significantly higher scores regarding the dental aesthetics component (3.84 vs 2.78, p < 0.001). Study groups were significantly different in terms of the prevalence of incisor overbite and open bite (p = 0.002 and p < 0.001, respectively). Patients in the ASD group showed a higher prevalence of Class II and Class III malocclusions (p < 0.001). CONCLUSION: ASD children obtained significantly higher overall ICON scores, indicating more complex and severe malocclusions. These children also exhibited a greater tendency towards Class II and III malocclusions.

Evaluation of Mandibular Projection in Class II Division 2 Subjects Following Orthodontic Treatment Using Clear Aligners.

AIM: The purpose of this study was to evaluate the mandibular growth and/or projection following maxillary incisor proclination, overbite correction, and maxillary dentoalveolar expansion without the use of any class II mechanics, in growing class II division 2 patients treated with clear aligners. MATERIALS AND METHODS: Before and after treatment cone-beam computed tomographic (CBCT) generated lateral and posteroanterior cephalograms of thirty-two patients with skeletal class II division 2, 16 in the treatment group and 16 in the untreated group, were reviewed to evaluate treatment-related changes. Upper incisors were proclined and protruded, as well as upper arch expansion and overbite correction were performed as part of their regular treatment. Cephalometric analysis was performed to evaluate skeletal and dental changes. Unpaired statistical t-tests were performed to determine if significant skeletal class II correction was achieved in the treatment group. RESULTS: In the treatment group, after treatment, the upper incisors became more proclined and protruded, and the inter-molar width increased while the overbite was reduced compared to the control group. An increase in skeletal mandibular growth and forward projection was also observed, thus contributing to an improvement of the sagittal skeletal relationship as evidenced by ANB and Wits values compared to the control group. CONCLUSION: A combination of upper incisor proclination, correction of deep overbite, and maxillary dentoalveolar expansion using clear aligners appears to contribute to an improvement of the skeletal class II relationship in growing patients with class II division 2. CLINICAL SIGNIFICANCE: This study shows that unlocking the mandible by correcting a deep overbite, proclining upper incisors, and expanding the upper arch in growing class II division 2 patients can improve skeletal class II using clear aligners. How to cite this article: Mirzasoleiman P, El-Bialy T, Wiltshire WA, et al. Evaluation of Mandibular Projection in Class II Division 2 Subjects Following Orthodontic Treatment Using Clear Aligners. J Contemp Dent Pract 2024;25(4):295-302.

A comprehensive national survey on malocclusion prevalence among Palestinian children.

BACKGROUND: This study aims to evaluate the prevalence of malocclusion and orthodontic features among schoolchildren in the West Bank, Palestine. METHODS: A stratified cluster sample of 1278 schoolchildren (620 males, 658 females, mean age 12 years and 5 months (± 0.5)) were examined. Candidates who had not received any previous orthodontic treatment were only included. Dental anomalies like missing and ectopic teeth were recorded. The anteroposterior occlusal relationship was assessed based on Angle classification. Overjet and overbite were measured. Crowding and spacing were recorded subjectively. In addition, crossbite, openbite, and midline displacement were recorded. The chi-square test and descriptive analysis were used statistically. RESULTS: The study found Angle Class I molar relationship in 65%, Class II div 1 in 17%, Class II div 2 in 6%, and Class III in 12% of the sample. An overjet (OJ) of more than 4 mm was present in 17%, and 4% had OJ of more than 6 mm; an OJ of at least 0 mm or less in 36%, and 6% had a reverse OJ. A normal overbite was observed in 53%, while 28% had an increase and 19% had a decreased overbite. An anterior openbite (AOB) was present in 9%, and a scissor bite or anterior crossbite in 6% and 14%, respectively. A posterior crossbite was observed in 12% (9% unilateral and 3% bilateral). Midline displacement was found in (9%). Crowding was observed in 35% and 31% and spacing in 24% and 15% of the maxillary and mandibular arches, respectively. A statistically significant relationship between gender and midline shift, a diastema, spacing in the upper arch, and most dental anomalies was found; males were more affected (p < 0.05). CONCLUSION: This study reported a high prevalence of malocclusion among schoolchildren in Palestine. A collaborative effort should be directed to obtain more monitoring and surveillance of malocclusion more frequently to prevent and control the exacerbation of the problem.

Uso de overlays controlados electromiográficamente y su combinación con el tratamiento con alineadores / Use of electromyographically controlled overlays and their combination with and its combination with treatment with aligners

La dimensión vertical (DV) usualmente disminuye con el paso del tiempo y es uno de los objetivos más complicados en resolver en los casos de Ortodoncia, ya sea con brackets o con alineadores. Esta disminución de la DV tiene una influencia directa en el funcionamiento de la articulación temporomandibular (ATM). Las patologías de la ATM, que surgen por la pérdida de la DV, son usualmente tratadas en la fase I con placas que restablecen la posición articular y la función muscular. Luego de corregida la patología de la ATM, en la fase II hay que tratar en lo posible la oclusión, devolviendo al paciente un soporte fisiológico posterior. Aquí se presenta un caso clínico atendido con una Placa Neurofisiológica (PN) en la fase I, y en la fase II, el traslado de esta altura a los overlays (O) y su erupción posterior dentaria con alineadores. Controlando cada paso electromiográficamente para el restablecimiento y control de la función muscular.

The vertical dimension usually decreases over time and is one of the most complicated objectives to solve in Orthodontic cases, whether with braces or aligners. This decrease in vertical dimension has a direct influence on the physiology of the temporomandibular joint. TMJ pathologies that arise from the loss of vertical dimension are usually treated in Phase I with splints that restore joint position and muscle function. After correcting the TMJ pathology, in Phase II, the occlusion should be treated as much as possible, returning the patient to a physiological posterior support. A clinical case is presented involving treatment with a Neurophysiological Splint in the first phase, and in the second phase, the transfer of this height to overlays and subsequent dental eruption with aligners. Each step is electromyographically monitored for the restoration and control of muscle function.

Analysis of prefabricated myofunctional appliances with different overjet and bumper designs: a three-dimensional finite element analysis.

BACKGROUND: Prefabricated myofunctional appliance can guide tooth eruption, improve dentition alignment, correct myofunctional disorders and harmful oral habits. However, its application to skeletal discrepancy may result in unsatisfactory tooth inclination. This study aimed to construct a novel appliance with overjet design to avoid this side effect and investigated its shape and mechanical changes under occlusion using three-dimensional finite element method. METHODS: We established three samples of prefabricated myofunctional appliances. The first one was edge to edge without overjet, and the outer shield of both jaws were flattened. The second one was 3 mm overjet with stepped the outer shield. The last one was 3 mm overjet, and the outer shield of both jaws were flatted, which meant the front wall of lower jaw was strengthened with bumper, termed as lower bumper. A complete dentition model was applied to the study. 150 N occlusal force was applied to each type of appliance and the deformation displacement and the changes in stress was recorded. RESULTS: The deformation was significant in the incisors regions, especially in the vertical and lateral dimensions. The maximum displacements of 3 mm overjet with step shield group were 7.08 mm (vertical), 3.99 mm (lateral), and 2.90 mm (sagittal), while it decreased to 3.92 mm(vertical), 1.94 mm (lateral), and 1.55 mm (sagittal) in overjet with bumper group. Moreover, the upper molar regions exhibited higher vertical and sagittal displacement in 3 mm overjet with step shield group, which were 3.03 mm (vertical) and 1.99 mm (sagittal), and the bumper design could decrease the maximum displacement to 1.72 mm (vertical) and 0.72 mm (sagittal). In addition, the Von Mises stress of appliances was analyzed, and results indicated that 3 mm overjet with step shield generated higher stress than other groups, with the maximum Von Mises stress was 0.9387 MP, which were 0.5858 and 0.5657 MP in edge to edge group and 3 mm overjet with lower bumper group, respectively. CONCLUSION: The prefabricated myofunctional appliances may cause deformation during occlusion. Compared to step shield group, the application of lower bumper exhibited better resistance to occlusal force.

Planned and achieved overjet and overbite changes following an initial series of Invisalign® aligners: A retrospective study of adolescent patients.

OBJECTIVE: The aim of the present study was to compare the changes in overjet and overbite measurements achieved in adolescent patients following an initial series of Invisalign® aligners (Align Technology, San Jose, California) with those planned by orthodontists via its ClinCheck® digital treatment planning facility. METHODS: Data provided by Align regarding patients who had completed an initial series of Invisalign® aligner treatment and were less than 18-years old were assessed in relation to pre-treatment, planned and achieved overjet and overbite measurements. Descriptive statistics, Wilcoxon rank-sum, Mann Whitney calculations were computed. RESULTS: A total of 290 patients satisfied inclusion criteria. The median (interquartile range (IQR)) age was 14.17 (13,15.42) years. The median achieved overjet and overbite changes were less than those planned (p<0.01) with 53.33% of the planned median overjet increase achieved and 52.94% of planned median overjet reduction achieved. Additionally, 58.33% of the planned median overbite increase was achieved and 55.55% of the planned median overbite reduction was achieved. A total of 21.52% patients recorded no change or an increase from pre-treatment to the achieved overjet where reduction was planned, whereas 41.67% recorded no change or a reduction in overjet where increase was planned. A total of 18.72% recorded no change or an increase in overbite where reduction was planned, whereas 20.75% recorded no change or a reduction in overbite where increase was planned. CONCLUSIONS: Less than 60% of the planned overjet and overbite changes per patient were achieved. Between 18.72 and 41.67% of patients experienced no change or changes in overjet and overbite in the opposite direction to that planned. This is likely to be clinically significant.

Effects of eruption guidance appliance in the early treatment of Class III malocclusion.

OBJECTIVES: To evaluate the dentoskeletal effects and effectiveness of the eruption guidance appliance in Class III patients in the mixed dentition. MATERIALS AND METHODS: The experimental group comprised 22 patients with Class III malocclusion and anterior cross-bite (12 males, 10 females, mean age 7.63 ± 0.96 years) treated with the eruption guidance appliance over a mean period of 1.72 ± 0.48 years. The control group comprised 22 untreated subjects (12 males, 10 females, mean age 7.21 ± 0.60 years) with Class III malocclusion. Lateral cephalometric radiographs were obtained at pretreatment (T1) and posttreatment (T2). Intergroup comparisons were performed with Mann-Whitney and t-tests (P < .05). RESULTS: In the experimental and control groups, the anteroposterior relationship between the maxilla and mandible (ANB angle) remained stable during the treatment period (T1 to T2). The mandibular plane angle decreased in the experimental group and increased in the control group. In the experimental group, the lower anterior face height increase and maxillary molar vertical development were significantly smaller compared to controls. Positive overjet was achieved in 54% of the experimental group. CONCLUSIONS: The eruption guidance appliance produced no change in the skeletal anteroposterior relationship. The anterior cross-bite/edge-to-edge relationship was corrected in only about half of the treated subjects.

Skeletal, dentoalveolar and soft tissue changes after stabilization splint treatment for patients with temporomandibular joint disorders.

BACKGROUND: Temporomandibular disorder (TMD) is a grouping of heterogeneous disorders with multifactorial origins. Stabilization splints (SS) have demonstrated an acceptable treatment effect in TMD. The possible changes at the skeletal, dental, and soft tissue levels need to be addressed to evaluate the benefit/risk ratio of this therapeutic procedure. Accordingly, this study aimed to three­dimensionally evaluate skeletal, dentoalveolar and soft tissue changes after SS treatment for patients with TMD. METHODS: This retrospective study included 74 adult patients with myofascial and/or intra-articular disorders (25 males and 49 females), with an average age of 22.88 ± 4.8 years, who underwent SS treatment. Pre- and post-treatment Cone beam computed tomography were analysed using Invivo 6.0.3 software. The primary outcome was the vertical skeletal and dentoalveolar changes, while the secondary outcomes were the anteroposterior skeletal, dentoalveolar and soft tissue changes. Paired t-test and Wilcoxon rank sum test were used for statistical analyses. RESULTS: For the primary outcome; skeletally, there was a significant increase in mandibular plane inclination (difference: 0.82°±1.37), decrease facial height ratio (difference: 0.45%±1.07) and at the dentoalveolar level, the inclination of the functional (FOP-SN, FOP-FH) and bisecting (BOP-SN, BOP-FH) occlusal planes exhibited a significant increase too (difference: 0.38 ± 1.43°, 0.49 ± 1.62°, 0.44 ± 1.29° and 0.41 ± 1.17°, respectively) and also a decrease in the overbite (difference: -0.54 ± 0.83). For the secondary outcomes; there was a significant decrease in mandibular position (SNB) (difference: 1.60 ± 1.36°) and increase in the overjet (difference: 0.93 ± 1.04, p < 0.001) and a significant lower lip retrusion (difference: 0.33 ± 1.01 mm p < 0.01), was observed too. CONCLUSIONS: SS therapy resulted in significant vertical skeletal and dentoalveolar changes that were manifested mainly by facial height ratio, mandibular and occlusal plane changes, and to a lesser extent, significant anteroposterior skeletal, dentoalveolar, and soft tissue changes in the form of mandibular position, increased overjet and a more retrusive lower lip. These changes should be considered during patients' selection prior to initiating SS therapy.