Molar Relationship Correction Research Articles

Actual contribution ratio of maxillary and mandibular molars for total molar relationship correction during maxillary molar sequential distalization using clear aligners with Class II elastics: A finite element analysis

Class II elastics, in combination with clear aligners (CA), are efficient for molar distalization. However, the effects of this combination on intermaxillary molar relationship correction have yet to be investigated. This study aimed to investigate the actual contribution ratio of the maxillary and mandibular molars for total molar relationship correction during maxillary molar distalization using Class II elastics with CA and further explore therapeutic recommendations for clinical practice. Finite element models (FEMs) were established, including the distalization of the second molars (Set I), followed by the distalization of the first molars (Set II). Model A simulated elastics attached by precision cutting, whereas Model B simulated elastics attached to buttons. Force magnitudes of 100 g, 150 g, and 200 g of force were applied. We recorded the contribution ratio of the maxillary and mandibular molars for total molar relationship correction, effective distalizing distance in 0.25 mm step distance, tipping and rotation angles, and the hydrostatic stress in the periodontal ligament. During maxillary molar distalization, mesialization of the mandibular molar had a notable contribution ratio for molar relationship correction. The mandibular first molar was mesialized with mesiolingual rotation tendency. Approximately half of the 0.25 mm step distance was occupied by maxillary molar distalization; the remainder was occupied by anchorage teeth mesialization and tipping or rotation. When traction forces increased, the total molar relationship correction and effective distalization increased; the mandibular molars mesialization contribution ratio also increased, as did rotation and inclination tendency. Precision cutting had a higher total molar relationship correction and more effective distalization than a button but also had a larger contribution ratio of mandibular molar mesialization and inclination or rotation. Mandibular molar mesialization should be considered when correcting the molar relationship using CA with intermaxillary elastics during maxillary molar distalization. It is also important to consider the anchorage teeth mesialization and undesired tipping or rotation.

Evaluation of Effects of Bimaxillary Anchored Fixed Functional Appliance on Temporomandibular Joint and Maxillomandibular Complex in Late Adolescents: An MRI Study

Objective To evaluate and assess changes in temporomandibular joint (TMJ), dental, skeletal and soft tissue changes following bimaxillary anchored fixed functional appliance (FFA) treatment of skeletal Class II malocclusion using Magnetic Resonance Imaging. Methods The prospective single-arm clinical trial included 15 patients (8 males, 7 females; mean age 15.71 + 1.81years) with Class II Division 1 malocclusion treated with bimaxillary anchored Forsus FRD. Four miniplates were placed bilaterally in maxilla and mandible. Then Forsus FRD L pin module was attached to miniplates without levelling of the arches. Pre-treatment (T1) and post-functional (T2) lateral cephalograms and MRI of TMJ were recorded. A total of 7 parameters were used to assess TMJ in all the 3 planes using MRI. Student’s t-test was carried out to compare pre- and post-treatment-induced changes. Results The mandible significantly moved forward (SNB, 3.71 + 0.91°; SND, 3.21 + 1.25°; Pg-OLp, 2.61 + 0.66 mm, p < 0.001) and there was distalizing effect on maxilla (SNA, –0.79 + 0.89°; A-OLp, –0.57 + 0.47mm, <0.001). Mean overjet correction of 4.43mm was achieved, of which 71.8% were skeletal changes. 65% of skeletal changes contributed to molar relationship correction. The forward positioning of mandible seems to be because of condylar and glenoid fossa remodelling, with condyle moving in anterior position within glenoid fossa (3.28 + 2.29) and articular disc moved posteriorly relative to condylar head (2.27 + 1.62°). Conclusion Significant skeletal changes and TMJ remodelling were observed with bimaxillary anchored FFA in correcting skeletal Class II malocclusion.

Dentoskeletal effects of the maxillary splint headgear in the early correction of Class II malocclusion

To compare dentoskeletal changes produced by the maxillary splint headgear and cervical headgear appliance during the early phase of Class II treatment, specially the initial overjet and upper incisors position. In this retrospective study, 28 Class II patients treated with the maxillary splint headgear (maxillary splint headgear or MSG, mean age 10.1 ± 1.9 years) and 28 Class II patients treated with cervical headgear (cervical headgear group or CHG, mean age 9.5 ± 1.9 years) were evaluated before and after treatment. Statistical comparisons between the two groups for cephalometric measurements at T1 and for T2-T1 changes were performed by means of independent sample t tests. The MSG showed a significantly greater reduction of the overjet in comparison to the CHG (-2.4 mm and -0.7 mm, respectively) and a significantly greater maxillary incisor uprighting (-1.8 mm and 0.4 mm, respectively). In the MSG, overjet correction was due mainly to mandibular advancement (3.5 mm), while the correction of molar relationship (3.9 mm) was 64% skeletal and 36% dentoalveolar. In the CHG, the overjet correction was also more skeletal, due to mandibular growth (1.8 mm), while correction of molar relationship (3.5 mm) was 63% dentoalveolar and 37% skeletal. Both groups showed favorable skeletal mandibular changes, which was more significant in the MSG. Regarding tooth movement, the maxillary splint headgear was more effective in uprighting upper incisors and reducing the overjet than cervical headgear appliance.

Dentoskeletal effects of the maxillary splint headgear in the early correction of Class II malocclusion

BackgroundTo compare dentoskeletal changes produced by the maxillary splint headgear and cervical headgear appliance during the early phase of Class II treatment, specially the initial overjet and upper incisors position.Subjects and methodsIn this retrospective study, 28 Class II patients treated with the maxillary splint headgear (MSG, mean age 10.1 ± 1.9 years) and 28 Class II patients treated with cervical headgear (CHG, mean age 9.5 ± 1.9 years) were evaluated before and after treatment. Statistical comparisons between the two groups for cephalometric measurements at T1 and for T2-T1 changes were performed by means of independent sample t tests.ResultsThe MSG showed a significantly greater reduction of the overjet in comparison to the CHG (− 2.4 mm and − 0.7 mm, respectively) and a significantly greater maxillary incisor uprighting (− 1.8 mm and 0.4 mm, respectively). In the MSG, overjet correction was due mainly to mandibular advancement (3.5 mm), while the correction of molar relationship (3.9 mm) was 64% skeletal and 36% dentoalveolar. In the CHG, the overjet correction was also more skeletal, due to mandibular growth (1.8 mm), while correction of molar relationship (3.5 mm) was 63% dentoalveolar and 37% skeletal.ConclusionsBoth groups showed favorable skeletal mandibular changes, which was more significant in the MSG. Regarding tooth movement, the maxillary splint headgear was more effective in uprighting upper incisors and reducing the overjet than cervical headgear appliance.

An Integrated Approach, Orthodontic and Prosthetic, in a Case of Maxillary Lateral Incisors Agenesis

Background: Among tooth anomalies, missing teeth is one of the most frequent, and it can be related to different therapeutical sets of problems. Often, an integrated approach that interests both orthodontists and prosthodontists is necessary, and in some cases also the periodontists. Methods: In this paper the authors report a clinical case of a 14-year-old patient, affected by maxillary bilateral incisors agenesis, molar bilateral II class and deep bite, treated in the Department of Orthodontics and Pedodontics of the University of Messina. The orthodontic treatment target was the distal movement of the maxillary molar, and the recovery of the space necessary for the prosthetic restoration of the missing lateral incisor. Maxillary molars distal movement was performed with a Distal Jet apparatus, skeletally supported by two miniscrews (Distal-Screw, American Orthodontics, Sheboygan, WI, USA). After molar relationship correction, a multi-bracket bimaxillary orthodontic appliance was bonded using Empower Brackets (American Orthodontics, Sheboygan, WI, USA). At the end of orthodontic treatment a Maryland bridge, bonded on the central incisors and cuspids, was used in order to maintain the space necessary for the insertion of dental implants in the region of 1.2 and 2.2 Results: A class II molar relationship was corrected, with an improvement of the deep bite, and the space necessary for implant insertion was recovered Conclusion: A skeletally supported Distal Jet was efficient for molar distalization, with the advantage of not having any loss of anchorage in the anterior part of the dental arch. This apparatus does not need patient compliance, have favorable aesthetics and also give the possibility to perform asymmetric activations.

Early correction of class II division 1 by the modified fixed lingual mandibular growth modificator

Objective: The aim of this study was to assess the skeletal and dental changes of Class II division 1 malocclusion corrected by Modified Fixed Lingual Mandibular Growth Modificator (MFLMGM). Materials and Method: This study was conducted on a sample of 15 patients, which they presented with CL II division 1 malocclusion. Overjet was ≥ 8mm. Age ranges from 9-12 year. The maxilla was protruded and the mandible was retruded. Results: The results showed that the maxillary growth was not significantly affected by MFLMGM treatment while the mandible was advanced. The overjet reduction was 7mm, and overbite reduction was 2.2mm. A reduction of 2.9o in ANB was largely due to an increase of 2.3o in SNB, slight non-significant increase in posterior facial height (S-GO) was 1.4mm. The changes in the other vertical skeletal relationships were negligible. Conclusion: Modified Fixed Lingual Mandibular Growth Modificator (MFLMGM) was successful in treatment cases of severe overjet skeletal Class II division 1 malocclusions. MFLMGM can control degree of severe overjet in treatment of skeletal Class II division 1 malocclusion by Gurin lock. Distal movement of upper molars were an important required in correction of molar relationship. Keywords: Fixed functional appliances, Class II correction, Mandibular advancement

Assessing changes in quality of life using the Oral Health Impact Profile (OHIP) in patients with different classifications of malocclusion during comprehensive orthodontic treatment.

BackgroundThe objectives of this study were to investigated changes in OHRQoL among patients with different classifications of malocclusion during comprehensive orthodontic treatment.MethodsClinical data were collected from 81 patients (aged 15 to 24) who had undergone comprehensive orthodontic treatment. Participants were classified 3 groups: Class I (n = 35), II (n = 32) and III (n = 14) by Angle classification. OHRQoL was assessed using the Oral Health Impact Profile (OHIP-14). All subjects were examined and interviewed at baseline (T0), after alignment and leveling (T1), after correction of molar relationship and space closure (T2), after finishing (T3). Friedman 2-way analysis of variance (ANOVA) and Wilcoxon signed rank tests were used to compare the relative changes of OHRQoL among the different time points. A Bonferroni correction with P < 0.005 was used to declare significance.ResultsSignificant reductions were observed in all seven OHIP-14 domains of three groups except for social disability (P > 0.005) in class I and class II, Handicap in class II and class III (P > 0.005). Class I patients showed significant changes for psychological disability and psychological discomfort domain at T1, functional limitation, physical pain at T2. Class III patients showed a significant benefit in all domains except physical pain and functional limitation. Class II patients showed significant changes in the physical pain, functional disability, and physical disability domains at T1.ConclusionsThe impact of comprehensive orthodontic treatment on patients’ OHRQoL do not follow the same pattern among patients with different malocclusion. Class II patients benefits the most from the stage of space closure, while class I patients benefits the first stage (alignment and leveling) of treatment in psychological disability and psychological discomfort domains.

Skeletal versus conventional intraoral anchorage for the treatment of class II malocclusion: dentoalveolar and skeletal effects.

BackgroundThe purpose of this retrospective study is to investigate the dentoalveolar and skeletal effects of two distalizing protocols featuring different anchorage systems used in patients with class II malocclusion: the MGBM system (skeletal anchorage) and Pendulum (intraoral anchorage).MethodsThe sample comprised 57 patients who were assigned to one of the two treatments: the MGBM group (30 patients, mean age 13.3 ± 2.3 years) or the Pendulum group (27 patients, mean age 12.8 ± 1.7 years). Three serial cephalograms were obtained at baseline (T0), after molar distalization (T1), and after fixed appliance treatment (T2). Esthetic, skeletal, and dental parameters were considered. Pancherz's superimposition method was used to assess sagittal dental changes. The initial and final measurements and treatment changes were compared by means of a paired t test or a paired Wilcoxon test. Statistical significance was tested at p < 0.05, p < 0.01, and p < 0.001.ResultsIn the MGBM group, the upper molar distalization was achieved in 7 months and showed a mean value of 4.9 mm (ms-PLO); the amount of molar relationship correction was 5.9 mm. In the Pendulum group, the upper molar distalization was obtained in 9 months and showed a mean value of 2.5 mm (ms-PLO), while the molar relationship correction amounted to 4.9 mm. Anterior anchorage loss occurred in both groups, although in the MGBM group, there was less mesial movement of the premolars.ConclusionsThe MGBM system and the Pendulum appliance are both effective in the correction of class II malocclusions. The MGBM system was found to be more efficient than the Pendulum appliance, producing greater molar distalization in a shorter treatment time.

Class II malocclusion with deep overbite: a sequential approach

OBJECTIVE: The aim of this case report was to evaluate the results of deep overbite correction by the segmented arch technique. METHODS: The first stage of the treatment was performed with this technique to intrude incisors and canines. A maxillary transpalatal bar and a mandibular lingual arch using 0.051-in archwire were employed associated to a facial bow, anchored primarily with occipital pull and, after molar relationship correction, changed to high pull. RESULTS: Upper incisors presented a great amount of intrusion and some palatal root inclination as programmed in the treatment plan. The skeletal mandibular response was favorable to achieve profile balance. Periapical radiograph showed rounded apex of incisor roots, expected in any orthodontic intrusion movement. CONCLUSION: The clinical results present the successful approach to deep overbite malocclusion.

Dentoskeletal effects of the fast-back molar distalizer followed by fixed appliances

IntroductionThe purpose of this study was to analyze the skeletal and dentoalveolar changes induced by the Fast-Back appliance followed by fixed appliances when compared with untreated Class II controls. Materials and methodsThe treated and untreated samples consisted of 27 subjects each (16 girls and 11 boys in the Fast-Back Group, FBG; 15 girls and 12 boys in the control Group, CG) with mean ages at the start of treatment of 13 years 3 months in the FBG and 13 years 2 months in the CG. Subjects of the FBG were treated during either the pubertal or postpubertal periods. Lateral cephalograms were analyzed at 2 observation periods: before distalization (T1) and after comprehensive orthodontic treatment appliance (T2). The T1-T2 changes in the FBG were contrasted with those in the CG by means of Mann-Whitney U test (p<0.05). ResultsTreatment induced an average correction of molar relationship of 2.4mm. The significant correction of the overjet (2.1mm) was associated with a significant amount of lower incisor proclination (3.8 degrees). A significant extrusion of lower molars (1.8mm) was recorded in the FBG. The FBG showed also a significant increase in total mandibular length (Co-Gn, 2.6mm), a counterclockwise rotation of the palatal plane (1.4 degrees), an increase in anterior facial height (N-Me, 2.7mm), and in mandibular ramus height (Co-Go, 2.6mm). ConclusionsThe Fast-Back is an effective appliance for Class II correction during the pubertal or postpubertal periods.

Stability of Class II, division 1 treatment with the headgear-activator combination followed by the edgewise appliance.

This study assessed the stability of the headgear-activator combination treatment, followed by edgewise mechanotherapy, 5.75 years after treatment. The experimental group consisted of 23 patients who were evaluated during treatment and after treatment. Two compatible control groups consisting of 15 Class II, division 1 patients and 24 normal occlusion individuals were used. This enabled us to evaluate the changes during treatment and after treatment, respectively. Results showed that the anteroposterior dentoalveolar changes and the maxillary and the mandibular positions remained stable in the long term. However, there was a slight relapse of the maxillomandibular relationship probably because the maxilla resumed its normal development and the mandibular growth rate was smaller than in the control group. The overbite demonstrated a statistically significant relapse that was directly proportional to the amount of its correction. There were low but significant inverse correlations between the changes in Go-Gn during and after treatment. These included the uprighting of the maxillary incisors, labial tipping of the mandibular incisors, and the amount of molar relationship correction during treatment and their stability. Active retention time, length of posttreatment period, initial Class II malocclusion severity (ANB and Wits), and initial molar relationship did not present any correlation with molar relationship and overjet relapse. However, the initial overjet presented a low but statistically significant correlation with molar relationship relapse and overjet relapse.

Comparison of Jones jig molar distalization appliance with extraoral traction

In this study, 20 patients were evaluated. Ten were treated with intraoral distalization followed by fixed appliance therapy, and 10 were treated with extra oral traction followed by fixed appliance therapy. Molar relationship correction was achieved in 2.5 months with intraoral distalization and in 10.7 months with extraoral distalization. A significant anterior movement of the anchorage unit ( P < .001) was observed with the intraoral distalization and a significant distal drift of premolars was observed in the headgear group ( P < .05). Palatal plane was found to tip downward significantly in the headgear group ( P < .05). Total outcome of the 2 methods were discussed evaluating the advantages and disadvantages of the 2 distalization methods. (Am J Orthod Dentofacial Orthop 2000;117:49-53)

A long-term evaluation of treated Class II division 2 malocclusions: a retrospective study model analysis.

Pre-treatment, end of treatment, and post-retention study models of 30 subjects with a Class II division 2 malocclusion were assessed, after a period of at least 3 years, in order to evaluate the long-term changes in occlusion, alignment, and arch dimensions. Molar relationship correction was found to be stable after retention. There were no variables which could be used to establish a prognosis of vertical stability. Over-correction of overbite was seen to relapse. Ten per cent of the cases showed unacceptable anterior maxillary irregularities after retention. Mandibular arch width and length usually showed a decrease after retention. An increase in lower intercanine width and arch length achieved by orthodontic treatment always relapsed. This relapse was associated with post-retention mandibular irregularity and crowding. Nine cases (30 per cent) showed an unacceptable degree of mandibular irregularity after retention. Pre-treatment crowding in the mandible showed a relationship with post-retention lower irregularity and crowding. There was a correlation between the number of years which had elapsed after retention, overbite relapse and post-retention mandibular irregularity.

Treatment of Class II malocclusions with the Jasper Jumper appliance—a preliminary report

The effect of the Jasper Jumper appliance (American Orthodontics, Sheboygan, Wis.) on the dentofacial complex was studied in 17 consecutive growing patients who had Class ll, Division 1 malocclusions. Lateral cephalograms taken before treatment and immediately after removal of the Jumpers were analyzed according to the method of Pancherz. The following results were found: (1) Class l occlusal relationships were achieved in all patients in an average treatment time of 6 months. (2) The correction of the Class ll malocclusion was a result of skeletal (40%) and dental (60%) changes. (3) Skeletal Class ll correction was predominantly restricted to the mandible. (4) The dentoalveolar part of total molar relationship correction took place to the same extent in both jaws, whereas in overjet correction the maxillary dental changes outweighed the mandibular changes by far. (5) When compared with normal growth changes (Bolton standards), treatment with Jasper Jumpers distalizes the upper dentition and moves the lower teeth mesially. Mandibular growth seems to be increased to some extent. It was concluded that treatment with the Jasper Jumper appliance presents an effective method to correct Class ll malocclusion in growing patients. (A M J O RTHOD D ENTOFAC O RTHOP 1995;108:341-50.)

Extra-oral traction and functional appliances--a cephalometric comparison.

The importance of correcting Angle's Class II molar relationships during orthodontic treatment is discussed and two methods of achieving this correction are described. The literature is reviewed and an investigation designed to compare the modes of action of extra-oral traction and functional appliances is described. The base line for cephalometric measurement is taken as S-N with a perpendicular axis constructed at S in order to minimize errors due to growth occurring during the investigation period. Results suggest that neither appliance has significant effects on the horizontal growth of the dental bases, but that the clinical effect of molar relationship correction is substantially due to dento-alveolar changes.