Intrusion Of Incisors Research Articles

Evaluation of True Incisor Intrusion Achieved with Single Mini Implant for Correction of Deep Overbite in Adult Patients

Evaluation of True Incisor Intrusion Achieved with Single Mini Implant for Correction of Deep Overbite in Adult Patients

Alveolar bone changes around maxillary incisors after intrusion and retraction with controlled tipping versus bodily movement : Aretrospective cone-beam computed tomography study.

To compare the effect of maxillary incisor intrusion and retraction with controlled tipping (CT) versus bodily movement (BM) in extraction cases on alveolar bone height and thickness, using cone-beam computed tomography (CBCT). Correlations between changes in alveolar dimensions and crown or root retraction, incisor inclination, and intrusion were also investigated. In all, 144 incisors of 36 women were retrospectively evaluated. All patients were treated with anterior intrusion and retraction with either controlled tipping (CT) (group1) or bodily movement (BM) (group2). CBCT scans were taken before and after retraction and intrusion and measurements of alveolar bone height and thickness at the level of mid-root and root apex were measured. The prevalence of dehiscence was also calculated. Labial bone thickness (BT) increased at the level of the root apex with increased total BT in the CT group (p < 0.05). The BM group showed decreased palatal BT. Significant vertical bone loss with an increased incidence of dehiscences occurred on the palatal side in both groups. Changes in palatal bone area was negatively correlated with the amount of root apex retraction, while the total BT at the level of root apex was positively correlated with amount of intrusion. Bodily retraction can result in reduced palatal bone dimensions and an increase risk of iatrogenic sequelae following anterior retraction in extraction cases. Vertical bone loss and an increased incidence of dehiscences is to be expected following anterior retraction. Careful attention must be paid to the bone boundary conditions to avoid moving the incisors out of the alveolar housing.

The consequences of orthodontic extrusion on previously intruded permanent incisors-A retrospective study.

The aim of this study is to compare the adverse effects that occur after orthodontic extrusion of teeth that have been traumatically intruded with those of similar teeth that have not experienced any trauma. The outcome of incisors intrusion can be affected by the patient's age, extent of injury, root development, and malocclusion. Orthodontic extrusion is a potential solution, but it may also cause complications. A retrospective study of the effects of extrusion of traumatically intruded teeth was carried out. The study group included 21 teeth in 14 patients. The control group included 32 teeth in 10 patients that underwent orthodontic extrusion with no history of trauma. Patients' age, gender, and stage of root development were recorded. The severity of the intrusion was classified as mild (<3 mm), moderate (3-6 mm), and severe (≥7 mm). A comparison of signs of pulp necrosis and root resorptions between the groups was made. The central incisor is the tooth that is most injured in 80.9% of cases. A majority of these incidents involve severe intrusion, which was found in 42.9% of cases. 90% of the traumatized teeth had already lost their vitality prior to orthodontic treatment. Various forms of root resorption were observed in the study group. In the control group, 31.2% of teeth showed signs of external root resorption, but no endodontic intervention was carried out during the follow-up period, as these teeth remained vital. Following intrusion, there is a high risk for root resorption and pulp necrosis. Orthodontic repositioning should be carried out with caution and mild force to prevent complications. Long-term follow-ups are required to ensure the best possible outcome.

The success rate of mini-screws for incisors intrusion and patient age, gender, and insertion angle in the maxilla using CBCT and implant-guided surgery. A split-mouth, randomized control trail.

The intrusion of anterior teeth is a routine procedure in orthodontics, which has been performed efficiently with the help of mini-screws in the anterior region, especially the upper maxilla. This study aimed to investigate the effect of insertion angle and sociodemographic features on the success rate of mini-screws at the anterior maxillary region. Twenty-nine patients (18 Females and 11 Males) aged 18-40 years old were involved in the current study. A split-mouth design was carried out in which recruited patients needed bilateral anterior screws at the labial bone in the region of the incisor for the intrusion of upper anterior incisor teeth as part of their orthodontic treatment with a fixed appliance (upper right side received 90-degree insertion angle mini-screw and 45° for left side) using a surgical guide fabricated from patients CBCT and intraoral scans. The mini-screws were inserted at the attached gingiva bilaterally to achieve intrusion of upper anterior teeth with a power chain ligated from the main archwire to the anterior min-implants. The patient was recalled monthly for orthodontic appliance activation and screw assessment for 6 months. The intrusion force was 15 g on each side. The results of the study showed that screw stability was higher in the male group than the female group at the 6th monthly follow-up visit with a statistically significant difference between both genders (P = .044). Concerning insertion angle, results showed a statistically significant difference between 45° and 90° as an insertion angle with a P-value <.01 in most of the follow-up months. This study found that male patients with mini-screws inserted at 90° showed greater screw stability over time.

Surgical Repositioning Following a Severe Traumatic Intrusion of Maxillary Permanent Incisors: A Case Report

: Intrusion is the most severe luxation injury, resulting in soft and hard tissue damage. Treatment depends on the root development stage and tooth intrusion degree. Lateral luxation describes tooth displacement in any direction other than axial. The prognosis of luxated teeth depends on the emergency treatment and elapsed time. This paper reports an 11-year-old boy who sustained displacement of central and lateral incisors into the nasal cavity, and his left canine had lateral luxation. Surgical repositioning was undertaken for intruded teeth, and a splint was placed. The canine could not be repositioned due to the delay, but its position improved toward the force of the cheek after several sessions. This study contains the data obtained from a one-year follow-up.

Cephalometric evaluation of deep overbite correction using anterior bite turbos.

To evaluate the outcome of treating deep overbite (OB) using anterior bite elevators concurrently with a pre-adjusted edgewise appliance. The Case Western Reserve University (CWRU) cephalometric analysis was used to isolate tipping movement of upper (TUI) and lower incisors (TLI), bodily tooth movement of upper (BUI), and lower incisors (BLI), as well as vertical skeletal changes in the anterior region of the maxilla (MXSK) and mandible (MNSK). Thirty treated subjects were examined at pretreatment (T1) and posttreatment (T2) and compared to an untreated control group matched on age, sex, and Angle malocclusion from the Bolton Brush Growth Study Collection (CWRU, Cleveland, Ohio). Overbite (OB) in the treated group was decreased significantly (P < .001) (-5.6 mm) compared to controls. Statistically significant (P < .001) changes were found for BUI (-0.7 mm), TUI (0.9 mm), TLI (-1.4 mm), BLI (-1.1 mm), and MNSK (-1.6 mm). Most of the overbite correction was in the lower arch and included tipping and intrusion of the lower incisors along with an increase in lower vertical facial height. Deep OB correction was achieved efficiently using anterior bite elevators with pre-adjusted edgewise appliance. Correction using bite turbos would be a treatment option for individuals presenting with decreased lower facial height and deep bite.

Finite element analysis of tooth movement under different retraction force and intrusive force in double-archwire lingual orthodontics system

The objectives of this study were to evaluate the tooth movement tendency during space closure in maxillary anterior teeth by various combinations of retraction force and intrusive force in a double-archwire lingual orthodontic system. Mini-implant-double slot lingual orthodontics system models of the bilateral maxillary first premolar extraction cases were constructed. Three-dimensional finite element models of the maxilla were constructed with definite position mini-implants (8 mm) and power arms (6 mm). Different retraction forces(50gf、100gf、150gf)were applied with the help of a nickel-titanium closed coil spring on the plate side. Intrusive forces(0gf、50gf、100gf)were applied with the help of the mini-implant between the two central incisors, and the initial displacements of the maxillary anterior teeth were analyzed. Variable amounts of displacements like controlled tipping, uncontrolled tipping, lingual crown tipping, labial root tipping, extrusion and distal crown tipping were observed in all the models, and these tendencies increased as the magnitude of retraction force increased, and these tendencies decreased as the magnitude of intrusive force increased. When the intrusive force was greater than or equal to the retraction force, the maxillary central incisors showed the trend of lingual crown tipping and labial root tipping, resulting in uncontrolled tipping movement. In terms of horizontal changes, the increasing width of bilateral anterior teeth was observed, with canines showing the least increasing trend. Various combinations of retraction force and intrusive force in a double-archwire lingual orthodontic system provide a new choice for torque control of the anterior teeth. Although anterior mini-implants and elastics can achieve incisor intrusion and lingual root torque, they cannot achieve the expected torque without additional torque control methods.

Effectiveness of clear aligners in achieving proclination and intrusion of incisors among Class II division 2 patients: a multivariate analysis

BackgroundThe predictability of incisor movement achieved by clear aligners among Class II division 2 patients is poorly understood. The aim of this retrospective study was to determine the effectiveness of clear aligners in proclining and intruding upper incisors and its influencing factors.MethodsEligible patients with Class II division 2 malocclusion were included. For clear aligner therapy, three types of incisor movements were designed: proclination, intrusion and labial movement. Pre-treatment and post-treatment dental models were superimposed. The differences between predicted and actual (DPA) tooth movement of incisors were analyzed. Univariate and multivariate linear regression were used to analyze the potential influencing factors.ResultsA total of 51 patients and their 173 upper incisors were included. Actual incisor proclination and intrusion were less than predicted ones (both P < 0.001), while actual labial movement was greater than predicted one (P < 0.001). Predictability of incisor proclination and intrusion was 69.8% and 53.3%, respectively. Multivariate linear regression revealed that DPA of proclination was significantly positively associated with predicted proclination (B = 0.174, P < 0.001), ipsilateral premolar extraction (B = 2.773, P < 0.001) and ipsilateral canine proclination (B = 1.811, P < 0.05), while negatively associated with molar distalization (B = − 2.085, P < 0.05). The DPA of intrusion was significantly positively correlated with predicted intrusion (B = 0.556, P < 0.001) while negatively associated with labial mini-implants (B = − 1.466, P < 0.001). The DPA of labial movement was significantly positively associated with predicted labial movement (B = 0.481, P < 0.001), while negatively correlated with molar distalization (B = − 1.004, P < 0.001), labial mini-implants (B = − 0.738, P < 0.001) and age (B = − 0.486, P < 0.05).ConclusionsFor Class II division 2 patients, predicted incisor proclination (69.8%) and intrusion (53.3%) are partially achieved with clear aligner therapy. Excessive labial movement (0.7 mm) of incisors may be achieved. Incisor movement is influenced by predicted movement amount, premolar extraction, canine proclination, molar distalization, mini-implants and age.

Biomechanical factors in the open gingival embrasure region during the intrusion of mandibular incisors: A new model through finite element analysis.

Introduction: Open gingival embrasure (OGE) is a common complication in adults following clear aligner therapy and the influence of gingival or alveolar bone biotype on OGE is of great concern. Unfortunately, due to the limited number of patients with clearaligner therapy and the clinical methods to distinguish the gingival biotype of patients being invasive, it is difficult to carry out clinical studies on the gingival or alveolar bone biotype of the OGE. In the meanwhile, the detailed biomechanics of the occurrence of OGE remains unknown. The goal of this study was to establish a new model to simulate the virtual space region, namely, the OGE region, to investigate the relationship between alveolar bone biotype and the occurrence of OGE, and explore potential biomechanical factors related to OGE. Methods: The OGE region in the interproximal space was established using a filler with a very low modulus of elasticity (1 × 10-6MPa). To illustrate the biomechanics of OGE more exhaustively, a line was created at the top of the alveolar crest along the proximal tooth root. FEA was then used to analyze the biomechanics of the surrounding tissues, the OGE region and the line at the top of the alveolar crest along the proximal tooth root of the central incisor under two different labial bone thicknesses (thick and thin) with an axial inclination of 80°, 90° and 100°. Results: During intrusion of the incisors in clear aligner therapy, as inclination increased or bone tissue became thinner, the stress in the surrounding tissues [tooth root, alveolar crest, and periodontal ligament (PDL)] was greater. In the OGE region and interproximal alveolar crest, the strain increased with increasing inclination and labial bone thinning. The results from the line at the top of the alveolar crest along the proximal tooth root showed more detailed biomechanics: In all groups, stress and strain were focused on the mesial-labial alveolar crest. Interestingly, our results also demonstrated that when OGE occurs, other complications may arise, including root resorption and bone dehiscence.

Mechanical loads exerted by different configurations of Burstone’s 3-piece segmented mechanics during a simulated intrusion of the mandibular incisors

Burstone's segmented intrusion arch technique allows variable incisor intrusion with lingual or labial tipping, depending on the position and direction of the force vectors exerted by the intrusion springs. To date, systematic biomechanical studies are lacking. This invitro study aimed to determine the 3-dimensional force-moment systems applied to the 4 mandibular incisors and the deactivation behavior of the appliance by different configurations of the 3-piece intrusion mechanics. The experimental setup consisted of a mandibular model segmented into 2 buccal and 1 anterior segment mounted on a 6-axis Hexapod to simulatedifferent incisor segment malpositions. Active elements were bilateral 0.017 × 0.025-in titanium-molybdenum alloy intrusion springs. Nine geometric appliance configurations at different superpositions of the anterior segment between 4 and 0 mm were evaluated. For 3-mm incisor superposition, mesiodistal variation of the contact of the intrusion spring at the anterior segment wire resulted in labial tipping moments between -0.11 and -1.6 Nmm. Variation of the height of force application at the anterior segment showed no significant influence on the tipping moments. During the simulated intrusion of the anterior segment, a force reduction rate of 21% per mm intrusion was observed. This study contributes to a more detailed and systematic understanding of the 3-piece intrusion mechanics and confirms the simplicity and predictability of the 3-piece intrusion. According to the measured reduction rate, the intrusion springs should be activated once every 2 months or 1-mm intrusion.

The Effects of Intrusion of Anterior Teeth by Skeletal Anchorage in Deep Bite Patients; A Systematic Review and Meta-Analysis.

Deep bite is known as one of the most common malocclusions, and its treatment and retention are often challenging. The use of mini-screws has been suggested as an ideal method for the intrusion of incisors in deep-bite patients. Still, there are conflicting reports regarding the superiority of this method compared to other common treatments. The aim of this systematic review and meta-analysis was to evaluate the effects of the intrusion of anterior teeth by skeletal anchorage in deep bite patients. From the beginning to 15 September 2022, articles on the topic of interest were searched in electronic databases including PubMed, Web of Science, Scopus, EMBASE, and Cochrane's CENTRAL. Additionally, a hand search for pertinent studies and a search of the grey literature were carried out. After the selection of eligible studies, data extraction was performed using piloted forms. Inverse-variance random-effects meta-analyses were used to combine the outcome measures of dental indices, skeletal cephalometric indices, and dental cephalometric indices. A total of 15 studies (6 RCT; 9 CCT) were included in the systematic review and 14 were used in the meta-analyses. The differences in overbite changes (MD = -0.45, p = 0.04), true incisor intrusion [u1-pp] (MD = -0.62, p = 0.003) and molar extrusion [u6-pp] (MD = -0.40, p = 0.01) were statistically significant and TADs showed better treatment results than other intrusion methods (segmented intrusion arch, utility arch, J hook headgear). No significant differences regarding overjet, molar and incisor tipping, and skeletal indices between mini-screw and other intrusion methods could be found. The use of mini-screws leads to lower overbite and higher true intrusion (about 0.45 and 0.62 mm, respectively) compared to the use of other methods for intruding upper incisors. Furthermore, the effect of TAD on extrusion of molar teeth is less (by 0.4 mm) than other methods.

Investigating the Effectiveness of Low-Level Laser in Reducing Root Resorption of the Upper Incisors During Intrusion Movement Using Mini-Implants in Adult Patients With Deep Overbite: A Randomized Controlled Clinical Trial.

Deep bite is a common characteristic of malocclusion, and many methods are used to treat it, including mini-implants used for the intrusion of the upper incisors. Orthodontically induced inflammatory root resorption (OIIRR) is an inevitable and unexpected side effect of orthodontic therapy. However, resorption of the root could be affected by the type of tooth movement, such as intrusion. Several studies have indicated the effectiveness of low-level laser therapy (LLLT) in accelerating orthodontic movement, but studies that have evaluated the role of this laser in reducing the risk of OIIRR have been limited. This trial aimed to investigate the effectiveness of LLLT in reducing the resorption of the roots of the upper incisors during their intrusion in the context of deep bite correction. Thirty patients (13 males, 17 females; mean age 22.4±3.37 years) with deep overbite were recruited and allocated to the laser or the control groups. Mini-implants were inserted between the roots of the upper central incisors and the lateral incisors from the labial aspect at the gingival-mucosal junction on both sides with a force of 40 g on each side through an NiTi coil spring. A low-level laser (Ga-Al-As) with 808 nm wavelength in a continuous mode, with the parameters250 milliwattpower output, 4 Joules/point energy density, and 16 seconds irradiation per point, was applied to the root of each of the upper incisors. The laser was applied on the first day of the upper incisor intrusion (T1), then on days 3, 7, and 14 of the first month. In the second month, the laser was applied every 15 days, adjusting the spring strength every four weeks until the end of the intrusion stage (T2), which was determined by reaching a normal overbite. As for patients in the control group, the strength of the nickel-titanium springs was adjusted every four weeks to the required strength of 40 g on each end until reaching a normal overbite. There was a volumetric decrease in both groups' upper central and lateral incisors roots, and this decrease was statistically significant (P<0.001). However, the difference between the two groups was not statistically significant in each central and lateral incisor volume root (P=0.345 and 0.263 for U1 and U2, respectively). Also, both groups had a linear decrease in upper central and lateral incisors roots, which was statistically significant (P<0.001). At the same time, the difference between the two groups was not statistically significant in each central and lateral incisor root length (P=0.343 and 0.461for U1 and U2, respectively). The low-level laser irradiation using the current protocol did not significantly affect the amount of root resorption induced by incisor intrusion in the experimental group compared to the control group.

Stress and movement trend of lower incisors with different IMPA intruded by clear aligner: a three-dimensional finite element analysis

BackgroundDuring the intrusion of lower incisors with clear aligners (CAs), root disengagement from the alveolar bone often occurs, resulting in serious complications. This study aimed to determine the potential force mechanism of the mandibular anterior teeth under the pressure of CA, providing theoretical data for clinical practice.MethodsIn this study, a 3D finite element model was established, including the CA, periodontal ligament, and mandibular dentition. Incisor mandibular plane angles were set as 5 groups: 90°, 95°, 100°, 105°, and 110°. The 4 mandibular incisors were intruded by 0.2 mm, while the canines were the anchorage teeth. The stress, force systems, and potential movement trends of mandibular anterior teeth were obtained.ResultsThe compressive stress of the incisors was concentrated in the lingual fossa, incisal ridge, and apex. With the increase in IMPA, the moment of central incisors changed from lingual crown moment to labial crown moment, with the turning point between 100° and 105°, but the center of resistance (CR) was always subjected to the force toward the lingual and intrusive direction. The force and moment toward the labial side of the lateral incisors were greater than those toward the central incisors. The canines always tipped distally and received extrusive force with no relationship with IMPA.ConclusionsWith the increase in the initial IMPA, the direction of labiolingual force on the mandibular incisors was reversed. However, the root of the lower incisors always tipped labially, which indicated fenestration and dehiscence.

Predictability of the deep overbite correction using clear aligners

The objective of this study was to investigate the predictability of overbite correction in patients with deepbite using the clear aligners (Invisalign, Align Technology, San Jose, Calif) and examine the accuracy of vertical movement and inclination change of individual teeth. This retrospective study included 24 deepbite patients (10 males and 14 females; aged 32.8 ± 11.9 years; an initial overbite of 5.20 ± 0.95 mm; an average treatment period of 11.04 ± 4.14 months) consecutively treated from September 2016 and completed before August 2021. SmartTrack materials were used for all patients. The initial, predicted, and achieved final models were exported from ClinCheck and superimposed via best-fit surface-based registration using Slicer CMF (version 4.9.0; cmf.slicer.org). The overbite correction, changes in vertical movement, and inclination for individual teeth were measured. Descriptive statistics and a paired t test or Wilcoxon signed-rank test were performed. P<0.05 was considered statistically significant. Mean overbite correction was 33%, with a 1.15 mm improvement after the first set of aligners. All teeth demonstrated statistically significant differences between planned and achieved amounts in vertical movement and inclination change, with the largest difference in maxillary central incisors. Mandibular incisor intrusion and mandibular premolar extrusion had similar accuracies. Regarding inclination change, maxillary central incisors showed the lowest accuracy of 13.3%. Clear aligner treatment showed an average of 33% overbite correction. Overcorrection and additional refinement treatments are needed in most patients with a deepbite.

Comparative cone-beam computed tomographic evaluation of maxillary incisor intrusion and associated root resorption: Intrusion arch vs mini-implants

Various literature has verified that apical root resorption is a common adverse effect of orthodontic treatment, particularly intrusion. Conventional radiographic techniques underestimated root lengths and overestimated tooth lengths. Cone-beam computed tomography (CBCT) is a useful diagnostic tool to detect orthodontically induced external apical root resorption. This prospective study aimed to compare maxillary incisor intrusion and associated root resorption via CBCT. Thirty patients aged 16-23 years, having a deepbite of 6-8 mm and excessive gingival display on smiling, were divided into 2 groups: group 1, with 15 patients who were treated with Burstone intrusion arch, and group 2 with 15 patients who were treated with mini-implants applying 100 g of intrusive force for 4 months with activation done every 4 weeks. During this 4-month study period, no treatment was performed other than the intrusion of incisors. CBCT scans were obtained before and after the intrusion phase of treatment to compare the amount of intrusion and associated root resorption among both groups. No significant difference was found in mean incisor intrusion between groups 1 and 2 (P= 0.772), with slightly more proclination of incisors in group 1, resulting in a significant (P= 0.018) increase in the vertical change of incisal edge in group 1. A statistically significant difference was found in root resorption among both groups (P= 0.004), with more root resorption in group2. The results of this study indicate intrusion with both the intrusion systems using appropriate intrusive forces is effective in opening the bite with slightly more external apical root resorption in the mini-implant group.

Root resorption of maxillary incisors after en masse intrusion and retraction with controlled tipping versus bodily movement in adults.

The purpose of this study was to evaluate and compare the incidence of orthodontically induced inflammatory root resorption (OIIRR) after en masse maxillary incisors intrusion and retraction with controlled tipping versus bodily movement using cone beam computed tomography (CBCT). This study is a retrospective study performed on CBCT scans of 36 adult females who had their maxillary first premolars extracted followed by en masse anterior retraction and intrusion using labial biocreative therapy type II. Subjects were divided into two groups of 18 subjects each based on the type of tooth movement required during en masse retraction: Group I; the controlled tipping group, and Group II; the bodily movement group. The amount of intrusion, crown and root retraction, change in incisor inclination, and difference in tooth length was measured from the CBCT scans. Independent t tests were used to compare the measurements between the two groups. Pearson rank correlation analysis was applied to identify the relationship between the mean dental changes and the mean changes in tooth length for all four upper incisors. OIIRR was found in all four maxillary incisors in both groups. No significant differences were found between the two groups. OIIRR was positively correlated to the amount of root apex retraction and negatively correlated to the change in incisor inclination. Anterior retraction and intrusion lead to obvious root resorption affecting all maxillary incisors. No significant differences were found between the two groups. Careful clinical monitoring is needed for patients requiring anterior retraction with intrusion with maximum anchorage.

The three-dimensional displacement tendency of teeth depending on incisor torque compensation with clear aligners of different thicknesses in cases of extraction: a finite element study

BackgroundDespite the popularity of clear aligner treatment, the effect of the thickness of these aligners has not been fully investigated. The objective of this study was to assess the effects of incisor torque compensation with different thicknesses of clear aligner on the three-dimensional displacement tendency of teeth in cases of extraction.MethodsThree-dimensional finite element models of the maxillary dentition with extracted first premolars, maxilla, periodontal ligaments, attachments, and aligners were constructed and subject to Finite Element Analysis (FEA). Two groups of models were created: (1) with 0.75 mm-thick aligners and (2) with 0.5 mm-thick aligners. A loading method was developed to simulate the action of clear aligners for the en masse retraction of the incisors. Power ridges of different heights were applied to both groups to mimic torque control, and the power ridges favoring the translation of the central incisors were selected. Then, we used ANSYS software to analyze the initial displacement of teeth and the principle stress on the PDL.ResultsDistal tipping, lingual tipping and extrusion of the incisors, distal tipping and extrusion of the canines, and mesial tipping and intrusion of the posterior teeth were all generated by clear aligner therapy. With the 0.5 mm-thick aligner, a power ridge of 0.7 mm could cause bodily retraction of the central incisors. With the 0.75 mm-thick aligner, a power ridge of 0.25 mm could cause translation of the central incisors. Aligner torque compensation created by the power ridges generated palatal root torque and intrusion of the incisors, intrusion of the canines, mesial tipping and the intrusion of the second premolar; these effects were more significant with a 0.75 mm-thick aligner. After torque compensation, the stress placed on the periodontal ligament of the incisors was distributed more evenly with the 0.75 mm-thick aligner.ConclusionsThe torque compensation caused by power ridges can achieve incisor intrusion and palatal root torque. Appropriate torque compensation with thicker aligners should be designed to ensure bodily retraction of anterior teeth and minimize root resorption, although more attention should be paid to the anchorage control of posterior teeth in cases of extraction.

Treatment of vertical problems with jaw functional orthopedics based on scientific evidence. Part 2: deep bite

The vertical problems of the stomatognathic system that alter the overbite, either by increasing in the deep bite (DB) or decreasing in the anterior open bite (AOB), are among the great challenges of the dentofacial corrections in the treatment and the retention and stability protocols. In this paper the state of art of DB treatment with Jaw Functional Orthopedics (JFO) will be discussed. JFO has a unique diagnostic tool for changes in vertical growth of the face, the Articular Compass, developed by Simões. Individuals with hypodivergence and DB are, usually, difficult to treat and more difficult to stabilize the obtained results. Since 1950-decade Planas advocate that the Equiplan – a metal accessory used in functional orthopedic appliances (FOA) is efficient in deep bite treatment by levelling the occlusal plane. Promising results are found with a P = 0,00, but in aweak evidence study design based on the scientific evidence pyramid. Much of the discussion of incisor intrusion or molar extrusion to treat DB seems to be solved with the use of Equiplan, but it still has no scientific evidence, only clinical evidence. In conclusion Randomized Clinical Trials are needed to investigate the efficiency and Modus Operandi of JFO to treat DB.

Three-dimensional digital assessment of typodont activations.

Wax typodonts are widely used as pre-clinical teaching tools to test and research the complex force systems created by archwire activations, however, a limitation is the inability to quantify the resultant statically indeterminate tooth movements. The aim of this study was to develop an analogue-to-digital typodont system to quantify the effects of archwire activations on individual typodont teeth in three dimensions. The typodont system was developed using CAD/CAM technology. Posterior expansion, squared, tapered, asymmetrical arch forms and reversed curve of Spee activations were tested with three repeats. The resulting three-dimensional movements of individual typodont teeth were assessed with six degrees of freedom (df). Cartesian coordinate systems were set for each tooth. Mesio-distal, bucco-lingual and intrusive-extrusive movements were assessed as changes in the location of the geometrically estimated centre of resistance in the x, y and z axes, respectively. Torque, tip and rotation movements were assessed as the rotations around the mesio-distal, bucco-lingual and intrusive-extrusive axes, respectively. Individual typodont tooth displacements from each activation could reliably be described with six df. The transversal-to-sagittal movement ratio ranged from 2:1 to 7:1, depending on the activation. Asymmetrical arch form activations caused a midline shift and affected the lateral overjet. Reversing the curve of Spee led to intrusion of incisors and second molars, extrusion of premolars and first molars and pronounced first and third order effects. The digital typodont system is a promising teaching tool. The tested activations have implications in three dimensions, which should be considered when planning tooth movements.

Alveolar Bone After Intrusion and Retraction of Anterior Teeth: Fractional Dimensional Analysis

Objective: To evaluate changes in the trabecular structure of alveolar bone in maxillary incisors segment after maxillary incisor intrusion and retraction with fixed orthodontic treatment in adult patients using fractal dimensional analysis (FD). Methods: This study was conducted using a digital panoramic radiograph of 30 patients (Age Group 18 - 25 years) with class II malocclusion with maxillary incisor protrusion treated with intrusion and retraction of anterior teeth. Panoramic radiographs were taken with standard protocols at the three different periods, before orthodontic treatment (T0), immediately after alignment but before intrusion and retraction (T1), and after intrusion & retraction of anterior teeth (T2). Regions of interest were located between the apices of maxillary incisors. Findings: Fractal dimension (FD) was calculated using ImageJ software. Repeated Measure ANOVA test; indicates significant difference at p0.05. FD values of the alveolar bone of maxillary incisors at T0 were 1.312  0.09, which reduced to 1.273  0.10 at T1 and again increased to 1.325  0.07 at T2. This overall change in FD values was significant (p=0.050. Novelty: The study revealed that, during orthodontic tooth movement, the alveolar bone around the teeth was reduced. However, after a period of bone recovery, the reduced bone density recovered to its previous state from before the orthodontic treatment. Keywords: Alveolar bone; Bone trabeculae; Fractal analysis; Orthodontic tooth movement; Panaromic radiograph