Movement Of Maxillary First Molars Research Articles

Mesial movement of maxillary first molars and vertical dimensional changes in orthodontic extraction treatment for patients with different facial morphology

Objectives: Primarily, to compare anchorage loss and changes in mandibular plane (MP) angle, overbite, and amount of horizontal, vertical, and angular movements of maxillary incisors in groups of hypodivergent, hyperdivergent, and normodivergent patients. Secondarily, to analyze the relationship between those factors. Methods: Pre- and post-treatment cephalograms of 89 patients treated with extraction of four bicuspids or two maxillary bicuspids were analyzed. The sample was divided into three groups based on their facial pattern measured by SN-MP angle (hypodivergent: < 270, hyperdivergent: >380, and normodivergent: 270-380). Linear and angular measurements included the distances of U1 tip and U6 mesial height of contour to Y-axis (i.e., line perpendicular to the X-axis, passing through Sella turcica), distance of U1 tip to Sella on X-axis, overbite, angulation of U1 to palatal plane, and SN-MP and ANB angles. Inferential statistics included one-way ANOVA, Chi-square test, independent t-test, and Pearson’s correlation coefficients. Results: Facial morphology did not primarily affect anchorage loss, because other factors such as crowding, severity of Class II molar relationship, and extraction modality played more impactful role (P< 0.01). Change in mandibular plane angle was neither influenced by, nor correlated with, initial facial morphology or anchorage loss (P> 0.05). Positive change in overbite was significantly correlated with facial pattern, incisor extrusion and retroclination (r= 0.30, 0.44, and -0.35, respectively, P< 0.01). Conclusion: Anchorage loss in extraction orthodontic treatment is not influenced primarily by initial facial morphology. Anchorage loss is not significantly associated with MP angle reduction. Change in overbite can be achieved through incisor extrusion and retroclination.

The effectiveness of traditional corticotomy vs flapless corticotomy in miniscrew-supported en-masse retraction of maxillary anterior teeth in patients with Class II Division 1 malocclusion: A single-centered, randomized controlled clinical trial

This single-centered, parallel-groups trial aimed to evaluate the efficacy of traditional corticotomy vs flapless corticotomy in accelerating en-masse retraction. In addition, to assess the skeletal, dental, and soft-tissue variables, as well as the external apical root resorption (EARR) of the maxillary anterior teeth. Forty patients with Class II Division 1 malocclusion aged>18years at the beginning of treatment, requiring maxillary first premolar extractions, were randomly distributed into 2 groups (n=20 each): 1 group was treated using traditional corticotomy, and the other group was treated with flapless corticotomy in en-masse retraction with anchorage based on miniscrews placed between maxillary second premolars and first molars bilaterally. Randomization was implemented with a computer-generated list of random numbers; allocation was concealed in sequentially numbered, opaque, sealed envelopes. The study was single-blinded (outcomes' assessor). The primary outcome was the en-masse retraction duration. Secondary outcomes were the skeletal, dental, and soft-tissue changes on lateral cephalometric and the EARR of maxillary anterior teeth on digital panoramic radiographs. The en-masse retraction duration in the flapless corticotomy group was longer than the traditional corticotomy group. The average retraction duration was 4.04±1.10months for the flapless corticotomy group and 3.75±2.14months for the traditional corticotomy group, with no significant difference between the 2 groups (95% confidence interval [CI], -0.81 to 1.39; P=0.59). No significant differences were observed between the 2 groups regarding changes in several lateral cephalometric variables (eg, SNA angle [95% CI, -2.55° to 1.66°; P=0.67], SN-U1angle [95% CI, -1.70° to 1.32°; P=0.80], and UL-E [95% CI: -1.33 to 1.00mm; P=0.78]) or in the amount of EARR in the maxillary anterior teeth (P=0.31). The proportion of the observed EARR ranged from 1% to 6% of root length in both corticotomy groups. No serious harms were observed in both groups. No significant differences between the flapless and traditional corticotomies were found in terms of the skeletal, dental, and soft-tissue variables as well as in the amount of EARR. Corticotomy-assisted en-masse retraction led to improvements in skeletal structures and facial profile and resulted in sufficient retraction of maxillary anterior teeth, slight distal movement of maxillary first molars, and an intrusion movement for both anterior and posterior teeth. Both corticotomy techniques did not cause significant EARR. ClinicalTrials.gov (Identifier: NCT03279042). The protocol was not published before the trial commencement.

Comparison of Skeletal and Dental Changes Obtained from a Tooth-Borne Maxillary Expansion Appliance Compared to the Damon System Assessed through a Digital Volumetric Imaging: A Randomized Clinical Trial.

The purpose of this study was to evaluate and compare dental and skeletal changes associated with the Damon and Rapid Maxillary Expander (RME) expansion using Cone-Beam Computed Tomography (CBCT). Eighty-two patients, from The University of Alberta Orthodontic Clinic, were randomly allocated to either Group A or B. Patients in Group A received orthodontic treatment using the Damon brackets. Patients in Group B received treatment using the Hyrax (a type of RME) appliance. CBCT images were taken two times (baseline and after expansion). The AVIZO software was used to locate 18 landmarks (dental and skeletal) on sagittal, axial, and coronal slices of CBCT images. Comparison between two groups showed that transverse movement of maxillary first molars and premolars was much greater in the Hyrax group. The lateral movements of posterior teeth were associated with buccal tipping of crowns. No clinically significant difference in the vertical or anteroposterior direction between the two groups was noted. Alveolar bone next to root apex of maxillary first premolar and molar teeth showed clinically significant lateral movement in the Hyrax group only. The comparison between two groups showed significantly greater transverse expansion of the first molar and first premolars with buccal tipping in the RME group.

Extraoral vs intraoral appliance for distal movement of maxillary first molars: a randomized controlled trial.

Using randomized controlled trial methodology, the aim of this study was to evaluate and compare the treatment effects of an extraoral appliance (EOA) and an intraoral appliance (IOA) for distal movement of maxillary first molars. A total of 40 patients (mean 11.5 years, SD 1.29) at the Orthodontic Clinic, National Health Service, Skane County Council, Malmö, Sweden, were randomized to receive treatment with either extraoral traction (cervical headgear) or an IOA using superelastic coils for distal movement of maxillary first molars. The inclusion criteria were a nonextraction treatment plan, a Class II molar relationship and maxillary first molars in occlusion with no erupted maxillary second molars. The outcome measures to be assessed in the trial were treatment time, cephalometric analysis of distal molar movement, anterior movement of maxillary central incisors, ie, anchorage loss and sagittal and vertical skeletal positional changes of the maxilla and mandible. In the IOA group, the molars were distalized during an average time of 5.2 months, whereas in the EOA group the corresponding time was 6.4 months (P < .01). The mean amount of distal molar movement was significantly higher in the IOA than in the EOA group, three mm vs 1.7 mm (P < .001). Moderate anchorage loss was produced with the IOA implying increased overjet (0.9 mm) whereas the EOA created decreased overjet (0.9 mm). It can be concluded that the IOA was more effective than the EOA to create distal movement of the maxillary first molars.

Comparison of achieved and predicted tooth movement of maxillary first molars and central incisors: First premolar extraction treatment with Invisalign.

To compare achieved and predicted tooth movements of maxillary first molars and central incisors in first premolar extraction cases treated with Invisalign. The present study included 30 patients who received maxillary first premolar extraction treatment with Invisalign. The actual posttreatment model was registered with the pretreatment model on the palatal stable region and superimposed with the virtual posttreatment model. Achieved and predicted tooth movements of maxillary first molars and central incisors were compared using paired t-test. Linear mixed-effect model analyses were used to explore the influence of age (adolescents vs adults), attachment (G6-optimized vs 3-mm vertical, 3-mm horizontal, and 5-mm horizontal), and initial crowding on the differences between predicted and achieved tooth movement (DPATM). First molars achieved greater mesial tipping, mesial translation, and intrusion than predicted. Central incisors achieved less retraction and greater lingual crown torque and extrusion than predicted. Adolescents showed greater DPATM in the mesiodistal translation of first molars and labiolingual translation of central incisors and smaller DPATM in the occlusogingival translation of the first molars and crown torque of the central incisors than adults. The 3-mm vertical attachment group showed greater DPATM in the mesiodistal translation of the first molars vs the G6-optimized attachment group. Initial crowding had an inverse correlation with DPATM in angulation and mesiodistal translation of the first molars. First molar anchorage control and central incisor retraction were not fully achieved as predicted in first premolar extraction treatment with Invisalign. Age, attachment, and initial crowding affected the differences between predicted and achieved tooth movement.

Soft tissue, skeletal and dentoalveolar changes following conventional anchorage molar distalization therapy in class II Non-growing subjects: a multicentric retrospective study

ObjectivesThe purpose of this retrospective prolective study is to evaluate soft tissue, dentoalveolar and skeletal vertical changes following conventional anchorage molar distalization therapy in adult patients. Materials and methodsForty-six patients (34 females, mean age 25 years 6 months; and 12 males, mean age 28 years 4 months) were recruited from 4 specialists Board Certified. All subjects underwent molar distalization therapy according different distalization mechanics. Cephalometric headfilms were available for all subjects before (T0) and at the end of comprehensive treatment (T1). The initial and final measurements and treatment changes were compared by means of a paired t-test or a paired Wilcoxon test. ResultsMean total treatment time was 3 years 3 months ± 8 months. Maxillary first and second molars distalized 2.16±0.84mm and 2.01±0.69mm respectively, but also maintained a slight distal tipping of 1.45° (min 2.22°, max -6.45°) and 3.35° (min 0.47°, max -15.48°) at the end of treatment. Distal movement of maxillary first molar contributed 57.6% to molar correction, and 42.4% was due to a mesial movement of mandibular first molar (1.59±0.46mm). Dentoalveolar changes contributed to overjet correction; maxillary incisors retroclined 5.78°±3.17°, lower incisors proclined 7.49°±4.52° and occlusal plane rotated down and backward 2.32°±2.10°. A significant clockwise rotation of the mandible (1.97°±1.32°) and a significant increase in lower facial height (3.35±1.48) mm were observed. Upper lip slightly retruded (-1.76±1.70mm) and lower lip protruded (0.96±0.99mm) but these changes had a negligible impact on clinical appearance. ConclusionsAlthough maxillary molar distalization therapy can be performed in adult patients, significant proclination of the lower incisors, clockwise rotation of the occlusal plane and increase in vertical facial dimension should be expected. Nevertheless, in absence of maxillary third molars and in presence of mandibular third molars this procedure could be recommended.

The effects of the Pendulum distalising appliance and cervical headgear on the dentofacial structures

Abstract Background: Headgears are effective in distalising maxillary molars, but success depends on patient compliance and tolerance. Intra-oral distalising appliances are simple to construct and use and may be a better alternative for patients who are non-compliant or cannot tolerate headgear. Aims: To compare the Pendulum (PEN) appliance and cervical headgear (CHG) on distal movement of maxillary first molars in patients requiring maxillary molar distalisation. Methods: Thirty patients were randomly divided into two groups. Both groups had comparable occlusal and cephalometric characteristics before treatment. Fifteen patients (9 girls, 6 boys) with a mean age of 11.45 ± 1.54 years (Range: 8.58–13.50 years) were treated with Pendulum appliances and 15 patients (10 girls, 5 boys) with a mean age of 11.72 ± 1.24 years (Range: 9.58–13.33 years) were treated with a Ricketts-type CHG. A pilot study of four patients estimated that the time required to distalise the maxillary molars with the Pendulum appliance was five months. Therefore, the end of treatment records for the CHG group were taken after 4.96 ± 0.35 months. Lateral and postero-anterior cephalometric radiographs were taken of both groups at the start (T1) and end of distalisation/treatment (T2). Changes in cephalometric measurements in the two groups were compared with Wilcoxon and Mann-Whitney U tests. Results: Measurements indicated that U6-ANS distance, overjet and U1-APo distance increased, U6-PP angle and U6-PTV distance reduced, and the molar relationship improved more in the PEN group compared with the CHG group. Statistically, significant right molar – left molar differences were found between the two groups. Distalisation produced significant side effects, resulting in distal tipping of the first molars and an increase in overjet, whereas the CHG reduced the overjet. Conclusion: The Pendulum appliance was more effective than the CHG in distalising the maxillary first molars.

ニッケルフリーチタン基形状記憶合金を利用したラットの矯正学的歯の移動に関する研究

The purpose of this study was to evaluate the performance and the usefulness of a newly developed Ni-free Ti-based shape memory alloy (SMA) wire in orthodontic tooth movement by comparing with a nickel-titanium (Ni-Ti) alloy wire. A Titanium-niobium-aluminum (Ti-24Nb3Al) SMA wire, which was considered to be biocompatible because it contained no nickel, was newly developed and mechanical property of this new alloy was improved by severe cold rolling reduction. Twenty-one male Wistar-strain rats (age; 6 weeks) were used in the animal experiment. A Ti-Nb-Al alloy wire and an orthodontic superelastic wire (Ni-Ti alloy wire) were set in the oral cavities of rats, and orthodontic palatal movement of maxillary first molars was performed with an initial load of 15 gf. The amount of tooth movement was measured and periodontal structures were histologically examined. The Ti-Nb-Al alloy wire was effective for palatal tooth movement without any adverse reaction in rats. There was no significant difference in the amount of tooth movement between the Ti-Nb-Al group and the Ni-Ti group. Histological observation of the periodontal tissues revealed no differences between the two groups. These results indicate that Ti-Nb-Al alloy wire has excellent mechanical properties suitable for orthodontic tooth movement, suggesting that Ti-Nb-Al wire may be used as a practical nickel-free shape memory and superelastic alloy wire for orthodontic treatment as a substitute for Ni-Ti alloy wire. [doi:10.2320/matertrans.48.367]

Orthodontic Tooth Movement in Rats Using Ni-Free Ti-Based Shape Memory Alloy Wire

The purpose of this study was to evaluate the performance and the usefulness of a newly developed Ni-free Ti-based shape memory alloy (SMA) wire in orthodontic tooth movement by comparing with a nickel-titanium (Ni-Ti) alloy wire. A Titanium-niobium-aluminum (Ti-24Nb-3A1) SMA wire, which was considered to be biocompatible because it contained no nickel, was newly developed and mechanical property of this new alloy was improved by severe cold rolling reduction. Twenty-one male Wistar-strain rats (age; 6 weeks) were used in the animal experiment. A Ti-Nb-Al alloy wire and an orthodontic superelastic wire (Ni-Ti alloy wire) were set in the oral cavities of rats, and orthodontic palatal movement of maxillary first molars was performed with an initial load of 15 gf. The amount of tooth movement was measured and periodontal structures were histologically examined. The Ti-Nb-Al alloy wire was effective for palatal tooth movement without any adverse reaction in rats. There was no significant difference in the amount of tooth movement between the Ti-Nb-Al group and the Ni-Ti group. Histological observation of the periodontal tissues revealed no differences between the two groups. These results indicate that Ti-Nb-Al alloy wire has excellent mechanical properties suitable for orthodontic tooth movement, suggesting that Ti-Nb-Al wire may be used as a practical nickel-free shape memory and superelastic alloy wire for orthodontic treatment as a substitute for Ni-Ti alloy wire.

Intraoral Maxillary Molar Distalization

To evaluate the maxillary molar distalization and anchorage loss in two groups, one before (MD 1 group) and one after (MD 2 group) eruption of second maxillary molars. After a sample size calculation, 20 patients were recruited for each group from patients who fulfilled the following criteria: no orthodontic treatment before distal molar movement, Class II molar relationship defined by at least end-to-end molar relationship, space deficiency in the maxilla, and use of an intra-arch NiTi coil appliance with a Nance appliance to provide anchorage. Patients in the MD 1 group were without any erupted second molars during the distalization period, whereas in the MD 2 group both the first and second molars were in occlusion at start of treatment. The main outcome measures to be assessed were: treatment time, ie, time in months to achieve a normal molar relation, distal movement of maxillary first molars, and anterior movement of maxillary incisors (anchorage loss). The mean age in the MD 1 group was 11.4 years; in the MD 2 group, 14.6 years. The amount of distal movement of the first molars was significantly greater (P < .01) and the anchorage loss was significantly lower (P < .01) in the group with no second molars erupted. The molar distalization time was also significantly shorter (P < .001) in this group, and thus the movement rate was two times higher. It is more effective to distalize the first maxillary molars before the second molars have erupted.

The Changes by the Distal Movement of Maxillary First Molars in the Gnathofacial Region

For the purpose of determining an influence in the gnathofacial region by a distal movement of the maxillary second molars, the author compared 19 cases of the maxillary protrusion who had worn the Kloehn type cervical pullgear longer than 1 year and 3 months with 19 controls who were diagnosed as the maxillary protursion cases but did not receive an orthodontic treatment.As a result of analyses of the serial cephalograms taken of these two groups, the author arrived at the following conclusions : 1. Movement of the maxillary second molars by use of a maxillary headgear influences the overall maxillary region of human face.2. With the experimental or treated cases, both the palatal and occlusal planes were observed to perform a clockwise rotation.On the other hand, SNA and point A became deviated downward.3. In the upper portion of face, the growths of individuals were found to play a stronger part than an orthodontic force and, for this reason, a degree of change owing to an orthodontic force was less than in other facial portions.4. Changes in the gnathofacial region were diverse in individual cases. However, within the scope of the present study in which the school-age subjects (111A and 111B) were selectively used, it was confirmed that as the general tendency an application of a maxillary headgear tended to inhibit the foreward growth of gnathofacial region with an attendant increased growth in the downward direction.Moreover, its effect extended to the sphenoid bone and its neighborhood. From this fact, its possible influence on the base of skull may be reasonally inferred.