Intrusion Of Mandibular Incisors Research Articles

Does age influence deep overbite correction with Invisalign? A prospective study evaluating mandibular incisor intrusion in adolescents vs adults.

To compare the accuracy of mandibular incisor intrusion with Invisalign (Align Technology, Santa Clara, Calif) in adolescents to that in adults. This prospective clinical study included 58 patients treated with either Invisalign Teen or Invisalign Full. Mandibular central and lateral incisors were measured on digital models created from intraoral scans. Predicted values were determined by superimposing the initial and final ClinCheck models, and achieved values were determined by superimposing the initial ClinCheck models and the digital models from the final scans. Individual teeth were superimposed with a best-fit analysis and measured using Compare software (version 8.1; GeoDigm, Falcon Heights, Minn). The mean accuracies of mandibular incisor intrusion were 63.5% in adolescents and 45.3% in adults, and this difference was statistically significant. The amounts of achieved intrusion were 1.7 mm in adolescents and 0.9 mm in adults, and this difference was also statistically significant. Overall, there was a weak negative correlation between age and accuracy; as age advanced, the accuracy of mandibular incisor intrusion diminished slightly. Mandibular incisor intrusion with Invisalign is significantly more accurate in adolescents than in adults. Orthodontists could contemplate reducing the degree of overcorrection for mandibular incisor intrusion in adolescents with deep overbites undergoing Invisalign Teen but still implementing the reverse curve of Spee mechanics.

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.

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.

Pure Mandibular Incisor Intrusion: A Finite Element Study to Evaluate the Segmented Arch Technique.

Leveling the curve of Spee is a commonly-used strategy to correct deep bites. Although several techniques have been proposed to intrude mandibular incisors (MI), flaring of these teeth is often observed and in many instances undesired. A three-dimensional (3D) finite element model (FEM) was used to locate the ideal point of force application (PFA) to achieve pure MI intrusion with the three-piece arches’ technique. It comprised (1) a 0.021 × 0.025 in. stainless steel (SS) wire that passively filled the slots of the canine and premolar brackets and the first and second molar tubes, bilaterally; (2) a 0.0215 × 0.0275 in. SS intrusion base arch (IBA) inserted into the MI brackets, that presented a step down distal to the lateral incisors brackets and a posterior extension arm; (3) titanium-molybdenum tip-back springs designed to apply the intrusion force, fitted inside the first molar gingival tube. Four PFA on the IBA were simulated (FEM 1, 2, 3, and 4). FEM 3 resulted in pure MI and was considered the ideal PFA. FEM1 and 2 showed intrusion and buccal crown flaring of the MI, whereas FEM4 resulted in intrusion and lingual crown flaring of those teeth. Clinicians may consider three-piece arch mechanics to achieve pure MI intrusion. However, they must be aware that when force was applied anteriorly or posteriorly to the ideal PFA, the incisors would incline labially or lingually, respectively.

Stress assessment of mandibular incisor intrusion during initial leveling in continuous arch system with different archwire shapes of superelastic nickel-titanium: A three-dimensional finite element study

INTRODUCTION: Orthodontic leveling of mandibular teeth with deep curve of Spee usually creates an intrusive force on mandibular incisors with labial tipping. After placing an archwire, a deactivation force causes tooth movement within the periodontal space which induces the first step and is the first signal for further remodeling processes. This study aimed to investigate stress distribution and types of mandibular incisor movement after initial leveling with different nickel-titanium (Ni-Ti) archwires using finite element analysis. MATERIALS AND METHODS: A three-dimensional finite element model of well-aligned mandibular teeth with a deep curve of Spee was created to investigate intrusive force on mandibular incisors within the periodontal ligament (PDL) space. Round, square, and rectangular superelastic Ni-Ti archwires of 0.016” in height were tested to compare stress magnitude and the pattern of distribution on the root surface and PDL as well as the pattern of tooth displacement between the archwires. RESULTS: Intrusive force by an archwire within the PDL space caused the highest stress at both labial and lingual cervical roots, but much higher stress was found at the labial than the lingual cervical roots. The highest labial stress was more cervical than lingual in all models. Round wires showed much higher stress than either square- or rectangular-shaped archwires. Displacement in the labial direction of round wires moved the farthest, whereas square and rectangular wires showed less labial displacement. CONCLUSIONS: Lower incisor intrusion with round wires produced more stress at the labial cervical root and tipped more labially compared to square and rectangular archwires.

Three-dimensional effects of the mini-implant-anchored Forsus Fatigue Resistant Device: A randomized controlled trial.

To detect three-dimensionally the effects of using mini-implant anchorage with the Forsus Fatigue Resistant Device (FFRD). The sample comprised 43 skeletal Class II females with deficient mandibles. They were randomly allocated into three groups: 16 patients (13.25 ± 1.12 years) received FFRD alone (Forsus group), 15 subjects (13.07 ± 1.41 years) received FFRD and mini-implants (FMI group), and 12 subjects (12.71 ± 1.44 years) were in the untreated control group. Three-dimensional analyses of cone beam computed tomographic images were completed, and the data were statistically analyzed. Class I relationship and overjet correction were achieved in 88% of the cases. None of the two treatment groups showed significant mandibular skeletal effects. In the FMI group, significant headgear effect, decrease in maxillary width, and increase in the lower facial height were noted. In the FMI group, retroclination of maxillary incisors and distalization of maxillary molars were significantly higher. Proclination and intrusion of mandibular incisors were significantly greater in the Forsus group. FFRD resulted in Class II correction mainly through dentoalveolar effects and with minimal skeletal effects. Utilization of mini-implant anchorage effectively reduced the unfavorable proclination and intrusion of mandibular incisors but did not produce additional skeletal effects.

Components of overbite correction in lingual orthodontics: Molar extrusion or incisor intrusion?

The aim of this study was to evaluate the components of overbite correction with the lingual Incognito(®) technique. The study was based on 45 files of patients with overbite treated with the Incognito(®) technique. The evaluation of overbite correction is assessed by comparing lateral cephalograms before and after treatment using QuickCeph 2000(®) software. All the statistical calculations were performed using Statview II software for Mac(®). The results revealed the efficiency of the Incognito(®) technique in overbite correction despite the absence of bite planes in the majority of cases. The components of this correction are, in order: intrusion of mandibular incisors, extrusion of mandibular molars, weak extrusion of maxillary molars and stability of the maxillary incisors. These were the results commonly found in previous studies on small samples. The study also demonstrated an increase of lower face height in extraction and non-extraction cases. The Incognito(®) technique is very efficient in overbite correction. As the main component of overbite correction is mandibular incisor intrusion, it seems crucial from the esthetic point of view to evaluate the smile line when overbite correction is needed.

Evaluation Of Dentofacial Changes Caused With Sabbagh Universal Spring In Mandibular Retrognathic Patients: A Pilot Study

This pilot study was done to evaluate the dentofacial changes induced by the sabbagh universal spring (sus2) used in mandibular retrognathic patients. The study was carried out on 54 lateral cephalometric radiograms taken before placement and after removal of sus2 in the treatment group and at the beginning and six months after in the control group. The patient selection criteria were as follows: skeletal and dental class ii malocclusion due to retrognathic mandible, normal or low-angle growth pattern, post-peak growth period and no extracted or congenitally missing permanent teeth. The statistical evaluation of the data suggested the following results: no significant sagittal and vertical skeletal changes were observed. The slight retrusion and extrusion of the maxillary incisors as well as the distinct protrusion and intrusion of mandibular incisors were found to be statistically significant. The occlusal plane rotated in clockwise direction as a result of these dentoalveolar changes. Overbite and overjet were reduced significantly in all patients. The changes related to soft tissue profile were limited. The correction of class ii malocclusion by sus² appliance in late-adolescence was achieved by only dentoalveolar changes. Thus, it can be an acceptable substitute to class ii elastics for noncompliant patients.

Management of Skeletal Class II, deep bite

Class II, Division 2 malocclusion is a clinical entity, which presents a considerable difficulty in the provision of the stable result. Management of deep bite in adults has always been critical and requires proper diagnosis, individualized treatment planning and efficient application of treatment technique. Treatment modality depends on various types of skeletal, dental, and soft tissue problems. The correction of deep bite includes one or more of maxillary incisor intrusion, mandibular incisor intrusion, mandibular incisor proclination, maxillary posterior tooth extrusion, mandibular posterior tooth extrusion, or an increase of the lower face height. This case report describes the orthodontic treatment of an adult patient, who had presented a skeletal Class II, hypo divergent jaw pattern, skeletal deep bite, angles Class II Division 2 Malocclusion. The patient was treated with a combination of orthodontics and surgical line of treatment.

Deepbite correction with incisor intrusion in adults: A long-term cephalometric study

The purpose of this study was to investigate the long-term stability of deep overbite correction with mandibular incisor intrusion with utility arches in adult patients. Pretreatment, posttreatment, and 5-years postretention lateral cephalograms of 31 patients (mean age, 26.8 years; range, 24.1-30.9 years) with Class II Division 1 malocclusion and deepbite, treated by maxillary first premolar extraction and mandibular incisor intrusion, were traced and measured. Significant decreases in overjet and overbite (6.4 ± 1.2 and 3.9 ± 0.7 mm, respectively), significant retroclination (17° ± 1.9°) and retraction (3.8 ± 1.1 mm) of the maxillary incisors, and significant increases in protrusion (0.8 ± 1.5 mm), proclination (0.6° ± 0.9°), and intrusion (2.6 ± 1.4 mm) of the mandibular incisors were observed at posttreatment. At postretention, there were statistically significant but clinically unimportant increases in overjet and overbite (0.4 ± 0.2 and 0.8 ± 0.4 mm, respectively) and extrusion of the mandibular incisors (0.8 ± 1.1 mm). Correction of deepbite in nongrowing patients by mandibular incisor intrusion with a utility arch can be considered effective and stable.

A cephalometric comparative study of class II correction with Sabbagh Universal Spring (SUS²) and Forsus FRD appliances

The purpose of this clinical prospective study was to compare the dentofacial changes produced by the Sabbagh Universal Spring (SUS(2)) and Forsus FRD appliances in late adolescent patients with Class II malocclusion, and quantify them in comparison with an untreated group. The study was carried out on 59 patients with skeletal and dental Class II malocclusion due to retrognatic mandible. Among these, 20 were treated with SUS(2), 20 were treated with FRD, and no treatment was done to 19 subjects as the control group. 36 cephalometric landmarks were identified on each lateral cephalometric radiograph. The effects of both appliances were dentoalveolar and no significant vertical and sagittal skeletal effect on maxilla and mandible was achieved. The retrusion and extrusion of the maxillary incisors as well as the protrusion and intrusion of mandibular incisors were found to be statistically significant in both treatment groups. Soft tissue profile improvement was limited in both treatment groups. Both appliances corrected Class II discrepancies through dentoalveolar changes; however lower incisor proclination was more prominent with the Forsus FRD.

Effects of mandibular incisor intrusion obtained using a conventional utility arch vs bone anchorage

To compare the dentofacial effects of mandibular incisor intrusion using mini-implants with those of a conventional incisor intrusion mechanic, the utility arch. Twenty-six deep-bite patients were enrolled to one of the two groups. In group 1 the mandibular incisors were intruded using a 0.16 × 0.22-inch stainless-steel segmental wire connected to two mini-implants. In group 2 the mandibular incisor intrusion was performed using a conventional utility arch. Conventional lateral cephalometric radiographs were taken at pretreatment and at the end of intrusion. Thirty landmarks were identified to measure 23 linear and 20 angular measurements. Intragroup comparisons were made using a paired t-test or a Wilcoxon test. Intergroup comparisons were made using a Student's t-test or a Mann-Whitney U-test. The duration of intrusion was 5 months for group 1 and 4 months for group 2. In the implant group, the mean amount of change was 0.4 mm/mo for the incisor tip and 0.3 mm/mo for the center of resistance, and in the utility arch group, the mean amount of change was 0.25 mm/mo for the incisor tip and 0.2 mm/mo for the center of resistance. The mandibular incisors showed an average protrusion of 7° in the implant group and 8° in the utility arch group. Incisor intrusion that was achieved using an implant-supported segmented archwire was no different than the movement achieved with a conventional intrusion utility arch. The only difference between the two methods was in the molar movement.

Efeitos do aparelho Jasper Jumper no tratamento da má oclusão de Classe II

OBJETIVO: o objetivo deste estudo foi avaliar os efeitos esqueléticos e dentoalveolares do tratamento de pacientes com má oclusão de Classe II com o aparelho Jasper Jumper associado ao aparelho ortodôntico fixo, comparados a um grupo controle não-tratado. MÉTODOS: a amostra foi constituída por 47 indivíduos, divididos em dois grupos: Grupo 1, contendo 25 pacientes com idade média de 12,72 anos, tratados com o aparelho Jasper Jumper por um tempo médio de 2,15 anos; Grupo 2 (controle), composto por 22 indivíduos com idade média de 12,67 anos, não-submetidos a tratamento ortodôntico e com má oclusão de Classe II, observados por um período médio de 2,12 anos. Foram avaliadas as telerradiografias ao início e ao final do tratamento ortodôntico para o Grupo 1 e do período de observação para o Grupo 2. As variáveis cefalométricas iniciais, finais e as alterações com o tratamento foram comparadas entre os grupos por meio do teste t independente. RESULTADOS: em comparação ao grupo controle, o grupo Jasper Jumper apresentou maior restrição do deslocamento anterior da maxila e maior retrusão maxilar, melhora da relação maxilomandibular, diminuição da convexidade facial, maior protrusão e intrusão dos incisivos inferiores e maior extrusão dos molares inferiores, além de maior diminuição dos trespasses horizontal e vertical e maior melhora da relação molar. CONCLUSÃO: a correção da Classe II no grupo tratado com o Jasper Jumper e aparelhagem fixa se deu principalmente devido à restrição do crescimento maxilar, protrusão e intrusão dos incisivos inferiores e extrusão dos molares inferiores.

Gingival response to mandibular incisor intrusion

The aims of the study were to evaluate the rate of accompanying gingival movement and the changes in attached and keratinized gingivae after orthodontic intrusion of mandibular incisors. The study was carried out with 16 subjects whose mandibular incisors were orthodontically intruded for the correction of overbite. The orthodontic intrusion was performed with the segmented utility arch technique. Periodontal indexes and the widths of attached and keratinized gingivae were recorded before and after treatment. The gingival movement in relation to orthodontic intrusion was determined by means of radioopacity with a specially designed metal device indicating the position of the gingival margin and the mucogingival junction on the cephalograms taken before treatment and after intrusion. There were no statistically significant changes in the width of attached and keratinized gingivae after treatment (P >.05). The gingival margin and the mucogingival junction moved in the same direction as the teeth by 79% and 62%, respectively. A statistically significant decrease of the clinical crown length was also observed (P <.05). These results suggest that orthodontic intrusion does not lead to significant changes in the width of attached and keratinized gingivae when adequate plaque control is maintained. The gingiva moves in the same direction with the tooth, yet considerably less. This might indicate the need for follow-up or gingival correction after intrusion therapy.

Age effects on orthodontic treatment: Adolescents contrasted with adults

Skeletodental treatment changes in 30 adolescent girls and 26 women who had Class II, Division 1 malocclusions were contrasted cephalometrically, primarily with the McNamara analysis. The data show that adult treatment does not obligate the practitioner to longer treatment. In this study, both age groups were treated in 2.5 years on the average. Apical base corrections were achieved with equal facility in both groups by the posterior remodeling of point A, and this (in conjunction with unrestrained mandibular growth) is the major source of correction in the adolescents. In adults, in whom growth is trivial, an appreciable source of sagittal correction is the steepening of the occlusal plane. Several sequelae of Class II elastic force occurred as by-products of molar correction in the adults: increased mandibular molar eruption, increased maxillary molar intrusion, increased maxillary incisor eruption, increased mandibular incisor intrusion, and steepening of the occlusal plane.

A study of the relationship between incisor intrusion and root shortening

Apical root shortening is one of the most common complications of orthodontic treatment. Force magnitude has been suggested as an important factor. Studies on the occurrence of root resorption show equivocal results. The aim of the present study was to evaluate the relationship between intrusion with low forces (25 gm) using utility arches in the bioprogressive technique and root shortening. Age, sex, facial type, treatment time, extraction versus nonextraction therapy, width of the symphysis, and the angle of the incisors to skeletal reference planes also were studied for their relationship to intrusion and root shortening. Root shortening was found to average 1.84 mm for maxillary incisors and 0.61 mm for mandibular incisors subjected to intrusive force. Intrusion of incisors in a population exhibiting growth was found to be one of “holding against growth” and in the upper arch to a change in angulation of the maxillary incisors. Furthermore, when extraction was a part of the orthodontic treatment, it was related to intrusion of maxillary incisors but not to intrusion of mandibular incisors. No relationship was found between the amount of root shortening and degree of intrusion achieved. However, a long treatment time was significantly correlated to root shortening. None of the other characteristics studied were related to either intrusion or root shortening. In the present study, it was found that intrusion with the utility arch type of technique is not related to amount of root shortening. The degree of root shortening was markedly higher in the maxilla than the mandible. In general, treatment time was the most significant factor for occurrence of root shortening. A review of cases exhibiting the most severe root shortening indicated that there are persons with high resorptive potential in whom root shortening occurs in both the mandible and the maxilla. In these patients the intrusion achieved was significantly related to the amount of root shortening observed. It may be concluded that control of treatment time is of importance especially when intrusion in the maxilla is performed. Furthermore, there are patients with a high resorptive potential in both the maxilla and mandible who need to be carefully monitored during intrusion.